path: root/doc/rfc/rfc9393.txt

Internet Engineering Task Force (IETF)                       H. Birkholz
Request for Comments: 9393                                Fraunhofer SIT
Category: Standards Track                            J. Fitzgerald-McKay
ISSN: 2070-1721                                 National Security Agency
                                                              C. Schmidt
                                                   The MITRE Corporation
                                                           D. Waltermire
                                                                    NIST
                                                               June 2023


                  Concise Software Identification Tags

Abstract

   ISO/IEC 19770-2:2015 Software Identification (SWID) tags provide an
   extensible XML-based structure to identify and describe individual
   software components, patches, and installation bundles.  SWID tag
   representations can be too large for devices with network and storage
   constraints.  This document defines a concise representation of SWID
   tags: Concise SWID (CoSWID) tags.  CoSWID supports a set of semantics
   and features that are similar to those for SWID tags, as well as new
   semantics that allow CoSWIDs to describe additional types of
   information, all in a more memory-efficient format.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc9393.

Copyright Notice

   Copyright (c) 2023 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
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   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Revised BSD License text as described in Section 4.e of the
   Trust Legal Provisions and are provided without warranty as described
   in the Revised BSD License.

Table of Contents

   1.  Introduction
     1.1.  The SWID and CoSWID Tag Lifecycle
     1.2.  Concise SWID Format
     1.3.  Requirements Notation
   2.  Concise SWID Data Definition
     2.1.  Character Encoding
     2.2.  Concise SWID Extensions
     2.3.  The concise-swid-tag Map
     2.4.  concise-swid-tag Co-constraints
     2.5.  The global-attributes Group
     2.6.  The entity-entry Map
     2.7.  The link-entry Map
     2.8.  The software-meta-entry Map
     2.9.  The Resource Collection Definition
       2.9.1.  The hash-entry Array
       2.9.2.  The resource-collection Group
       2.9.3.  The payload-entry Map
       2.9.4.  The evidence-entry Map
     2.10. Full CDDL Specification
   3.  Determining the Type of CoSWID
   4.  CoSWID Indexed Label Values
     4.1.  Version Scheme
     4.2.  Entity Role Values
     4.3.  Link Ownership Values
     4.4.  Link Rel Values
     4.5.  Link Use Values
   5.  "swid" and "swidpath" Expressions
     5.1.  "swid" Expressions
     5.2.  "swidpath" Expressions
   6.  IANA Considerations
     6.1.  CoSWID Items Registry
     6.2.  Registries for Software ID Values
       6.2.1.  Registration Procedures
       6.2.2.  Private Use of Index and Name Values
       6.2.3.  Expert Review Criteria
       6.2.4.  Software ID Version Scheme Values Registry
       6.2.5.  Software ID Entity Role Values Registry
       6.2.6.  Software ID Link Ownership Values Registry
       6.2.7.  Software ID Link Relationship Values Registry
       6.2.8.  Software ID Link Use Values Registry
     6.3.  swid+cbor Media Type Registration
     6.4.  CoAP Content-Format Registration
     6.5.  CBOR Tag Registration
     6.6.  URI Scheme Registrations
       6.6.1.  URI Scheme "swid"
       6.6.2.  URI Scheme "swidpath"
     6.7.  CoSWID Model for Use in SWIMA Registration
   7.  Signed CoSWID Tags
   8.  CBOR-Tagged CoSWID Tags
   9.  Security Considerations
   10. Privacy Considerations
   11. References
     11.1.  Normative References
     11.2.  Informative References
   Acknowledgments
   Contributors
   Authors' Addresses

1.  Introduction

   SWID tags, as defined in ISO-19770-2:2015 [SWID], provide a
   standardized XML-based record format that identifies and describes a
   specific release of software, a patch, or an installation bundle,
   which are referred to as software components in this document.
   Different software components, and even different releases of a
   particular software component, each have a different SWID tag record
   associated with them.  SWID tags are meant to be flexible and able to
   express a broad set of metadata about a software component.

   SWID tags are used to support a number of processes, including but
   not limited to:

   *  Software Inventory Management, representing a part of a Software
      Asset Management process [SAM], which requires an accurate list of
      discernible deployed software components.

   *  Vulnerability Assessment, which requires a semantic link between
      standardized vulnerability descriptions and software components
      installed on IT assets [X.1520].

   *  Remote Attestation, which requires a link between Reference
      Integrity Manifests (RIMs) and Attester-produced event logs that
      complement attestation evidence [RFC9334].

   While there are very few required fields in SWID tags, there are many
   optional fields that support different uses.  A SWID tag consisting
   of only required fields might be a few hundred bytes in size;
   however, a tag containing many of the optional fields can be many
   orders of magnitude larger.  Thus, real-world instances of SWID tags
   can be fairly large, and the communication of SWID tags in usage
   scenarios, such as those described earlier, can cause a large amount
   of data to be transported.  This can be larger than acceptable for
   constrained devices and networks.  Concise SWID (CoSWID) tags
   significantly reduce the amount of data transported as compared to a
   typical SWID tag through the use of the Concise Binary Object
   Representation (CBOR) [RFC8949].

   Size comparisons between XML SWID and CoSWID mainly depend on domain-
   specific applications and the complexity of attributes used in
   instances.  While the values stored in CoSWID are often unchanged and
   therefore not reduced in size compared to an XML SWID, the
   scaffolding that the CoSWID encoding represents is significantly
   smaller by taking up 10 percent or less in size.  This effect is
   visible in representation sizes, which in early experiments benefited
   from a 50 percent to 85 percent reduction in generic usage scenarios.
   Additional size reduction is enabled with respect to the memory
   footprint of XML parsing/validation.

   In a CoSWID, the human-readable labels of SWID data items are
   replaced with more concise integer labels (indices).  This approach
   allows SWID and CoSWID to share a common implicit information model,
   with CoSWID providing an alternate data model [RFC3444].  While SWID
   and CoSWID are intended to share the same implicit information model,
   this specification does not define this information model or a
   mapping between the two data formats.  While an attempt to align SWID
   and CoSWID tags has been made here, future revisions of ISO/IEC
   19770-2:2015 or this specification might cause this implicit
   information model to diverge, since these specifications are
   maintained by different standards groups.

   The use of CBOR to express SWID information in CoSWID tags allows
   both CoSWID and SWID tags to be part of an enterprise security
   solution for a wider range of endpoints and environments.

1.1.  The SWID and CoSWID Tag Lifecycle

   In addition to defining the format of a SWID tag record, ISO/IEC
   19770-2:2015 defines requirements concerning the SWID tag lifecycle.
   Specifically, when a software component is installed on an endpoint,
   that software component's SWID tag is also installed.  Likewise, when
   the software component is uninstalled or replaced, the SWID tag is
   deleted or replaced, as appropriate.  As a result, ISO/IEC
   19770-2:2015 describes a system wherein there is a correspondence
   between the set of installed software components on an endpoint and
   the presence of the corresponding SWID tags for these components on
   that endpoint.  CoSWIDs share the same lifecycle requirements as a
   SWID tag.

   The SWID specification and supporting guidance provided in NIST
   Internal Report (NISTIR) 8060 ("Guidelines for the Creation of
   Interoperable Software Identification (SWID) Tags") [SWID-GUIDANCE]
   define four types of SWID tags: primary, patch, corpus, and
   supplemental.  The following text is paraphrased from these sources.

   Primary Tag:  A SWID or CoSWID tag that identifies and describes an
      installed software component on an endpoint.  A primary tag is
      intended to be installed on an endpoint along with the
      corresponding software component.

   Patch Tag:  A SWID or CoSWID tag that identifies and describes an
      installed patch that has made incremental changes to a software
      component installed on an endpoint.  A patch tag is intended to be
      installed on an endpoint along with the corresponding software
      component patch.

   Corpus Tag:  A SWID or CoSWID tag that identifies and describes an
      installable software component in its pre-installation state.  A
      corpus tag can be used to represent metadata about an installation
      package or installer for a software component, a software update,
      or a patch.

   Supplemental Tag:  A SWID or CoSWID tag that allows additional
      information to be associated with a referenced SWID tag.  This
      allows tools and users to record their own metadata about a
      software component without modifying CoSWID primary or patch tags
      created by a software provider.

   The type of a tag is determined by specific data elements, which are
   discussed in Section 3.  Section 3 also provides normative language
   for CoSWID semantics that implement this lifecycle.  The following
   information helps to explain how these semantics apply to the use of
   a CoSWID tag.

   Corpus, primary, and patch tags have similar functions in that they
   describe the existence and/or presence of different types of software
   components (e.g., software installers, software installations,
   software patches) and, potentially, different states of these
   software components.  Supplemental tags have the same structure as
   other tags but are used to provide information not contained in the
   referenced corpus, primary, and patch tags.  All four tag types come
   into play at various points in the software lifecycle and support
   software management processes that depend on the ability to
   accurately determine where each software component is in its
   lifecycle.

                                    +------------+
                                    v            |
  Software      Software        Software     Software      Software
  Deployment -> Installation -> Patching  -> Upgrading  -> Removal

  Corpus        Primary         Primary      xPrimary      xPrimary
  Supplemental  Supplemental    Supplemental xSupplemental xSupplemental
                                Patch        xPatch
                                             Primary
                                             Supplemental

           Figure 1: Use of Tag Types in the Software Lifecycle

   Figure 1 illustrates the steps in the software lifecycle and the
   relationships among those lifecycle events supported by the four
   types of SWID and CoSWID tags.  A detailed description of the four
   tag types is provided in Section 2.3.  The figure identifies the
   types of tags that are used in each lifecycle event.

   There are many ways in which software tags might be managed for the
   host the software is installed on.  For example, software tags could
   be made available on the host or to an external software manager when
   storage is limited on the host.

   In these cases, the host or external software manager is responsible
   for management of the tags, including deployment and removal of the
   tags as indicated by the above lifecycle.  Tags are deployed, and
   previously deployed tags are typically removed (indicated by an "x"
   prefix) at each lifecycle stage as follows:

      Software Deployment:  Before the software component is installed
         (i.e., pre-installation), and while the product is being
         deployed, a corpus tag provides information about the
         installation files and distribution media (e.g., CD/DVD,
         distribution package).

   Corpus tags are not actually deployed on the target system but are
   intended to support deployment procedures and their dependencies at
   install time, such as to verify the installation media.

      Software Installation:  A primary tag will be installed with the
         software component (or subsequently created) to uniquely
         identify and describe the software component.  Supplemental
         tags are created to augment primary tags with additional site-
         specific or extended information.  While not illustrated in the
         figure, patch tags can also be installed during software
         installation to provide information about software fixes
         deployed along with the base software installation.

      Software Patching:  When a patch is applied to the software
         component, a new patch tag is provided, supplying details about
         the patch and its dependencies.  While not illustrated in the
         figure, a corpus tag can also provide information about the
         patch installer and patching dependencies that need to be
         installed before the patch.

      Software Upgrading:  As a software component is upgraded to a new
         version, new primary and supplemental tags replace existing
         tags, enabling timely and accurate tracking of updates to
         software inventory.  While not illustrated in the figure, a
         corpus tag can also provide information about the upgrade
         installer and dependencies that need to be installed before the
         upgrade.

            |  Note: In the context of software tagging, software
            |  patching and updating differ in an important way.  When
            |  installing a patch, a set of file modifications are made
            |  to pre-installed software; these modifications do not
            |  alter the version number or the descriptive metadata of
            |  an installed software component.  An update can also make
            |  a set of file modifications; in that case, the version
            |  number or the descriptive metadata of an installed
            |  software component is changed.

      Software Removal:  Upon removal of the software component,
         relevant SWID tags are removed.  This removal event can trigger
         timely updates to software inventory reflecting the removal of
         the product and any associated patch or supplemental tags.

   As illustrated in the figure, supplemental tags can be associated
   with any corpus, primary, or patch tag to provide additional metadata
   about an installer, installed software, or installed patch,
   respectively.

   Understanding the use of CoSWIDs in the software lifecycle provides a
   basis for understanding the information provided in a CoSWID and the
   associated semantics of this information.  Each different SWID and
   CoSWID tag type provides different sets of information.  For example,
   a "corpus tag" is used to describe a software component's
   installation image on an installation medium, while a "patch tag" is
   meant to describe a patch that modifies some other software
   component.

1.2.  Concise SWID Format

   This document defines the CoSWID tag format, which is based on CBOR.
   CBOR-based CoSWID tags offer a more concise representation of SWID
   information as compared to the XML-based SWID tag representation in
   ISO-19770-2:2015.  The structure of a CoSWID is described via the
   Concise Data Definition Language (CDDL) [RFC8610].  The resulting
   CoSWID data definition is aligned with the information able to be
   expressed with the XML Schema definition of ISO-19770-2:2015 [SWID].
   This alignment allows both SWID and CoSWID tags to represent a common
   set of software component information and allows CoSWID tags to
   support the same uses as a SWID tag.

   The vocabulary (i.e., the CDDL names of the types and members used in
   the CoSWID CDDL specification) is mapped to more concise labels
   represented as small integer values (indices).  The names used in the
   CDDL specification and the mapping to the CBOR representation using
   integer indices are based on the vocabulary of the XML attribute and
   element names defined in ISO/IEC 19770-2:2015.

1.3.  Requirements Notation

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in
   BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

2.  Concise SWID Data Definition

   The following describes the general rules and processes for encoding
   data using CDDL representation.  Prior familiarity with CBOR and CDDL
   concepts will be helpful in understanding this CoSWID specification.

   This section describes the conventions by which a CoSWID is
   represented in the CDDL structure.  The CamelCase notation
   [CamelCase] used in the XML Schema definition is changed to a hyphen-
   separated notation [KebabCase] (e.g., "ResourceCollection" is named
   "resource-collection") in the CoSWID CDDL specification.  This
   deviation from the original notation used in the XML representation
   reduces ambiguity when referencing certain attributes in
   corresponding textual descriptions.  An attribute referred to by its
   name in CamelCase notation explicitly relates to XML SWID tags; an
   attribute referred to by its name in KebabCase notation explicitly
   relates to CBOR CoSWID tags.  This approach simplifies the
   composition of further work that will reference both XML SWID and
   CBOR CoSWID documents.

   In most cases, mapping attribute names between SWID and CoSWID can be
   done automatically by converting between CamelCase and KebabCase
   attribute names.  However, some CoSWID CDDL attribute names show
   greater variation relative to their corresponding SWID XML Schema
   attributes.  This is done when the change improves clarity in the
   CoSWID specification.  For example, the "name" and "version" SWID
   fields correspond to the "software-name" and "software-version"
   CoSWID fields, respectively.  As such, it is not always possible to
   mechanically translate between corresponding attribute names in the
   two formats.  In such cases, a manual mapping will need to be used.
   XPath expressions [W3C.REC-xpath20-20101214] need to use SWID names;
   see Section 5.2.

   The 57 human-readable text labels of the CDDL-based CoSWID vocabulary
   are mapped to integer indices via a block of rules at the bottom of
   the definition.  This allows a more concise integer-based form to be
   stored or transported, as compared to the less efficient text-based
   form of the original vocabulary.

   Through the use of CDDL-based integer labels, CoSWID allows for
   future expansion in subsequent revisions of this specification and
   through extensions (see Section 2.2).  New constructs can be
   associated with a new integer index.  A deprecated construct can be
   replaced by a new construct with a new integer index.  An
   implementation can use these integer indices to identify the
   construct to parse.  The "CoSWID Items" registry, defined in
   Section 6.1, is used to ensure that new constructs are assigned a
   unique index value.  This approach avoids the need to have an
   explicit CoSWID version.

   In a number of places, the value encoding admits both integer values
   and text strings.  The integer values are defined in a registry
   specific to the kind of value; the text values are not intended for
   interchange and are exclusively meant for private use as defined in
   Section 6.2.2.  Encoders SHOULD NOT use string values based on the
   names registered in the registry, as these values are less concise
   than their index value equivalent; a decoder MUST, however, be
   prepared to accept text strings that are not specified in this
   document (and ignore the construct if a string is unknown).  In the
   rest of this document, we call this an "integer label with text
   escape".

   The root of the CDDL specification provided by this document is the
   rule coswid (as defined in Section 8):

   start = coswid

   In CBOR, an array is encoded using bytes that identify the array, and
   the array's length or stop point (see [RFC8949]).  To make items that
   support one or more values, the following CDDL notation is used.

   _name_ = (_label_ => _data_ / [ 2* _data_ ])

   The CDDL rule above allows either a single data item or an array of
   two or more data values to be provided.  When a singleton data value
   is provided, the CBOR markers for the array, array length, and stop
   point are not needed, saving bytes.  When two or more data values are
   provided, these values are encoded as an array.  This modeling
   pattern is used frequently in the CoSWID CDDL specification to allow
   for more efficient encoding of singleton values.

   Usage of this construct can be simplified using

   one-or-more<T> = T / [ 2* T ]

   simplifying the above example to

   _name_ = (_label_ => one-or-more<_data_>)

   The following subsections describe the different parts of the CoSWID
   model.

2.1.  Character Encoding

   The CDDL "text" type is represented in CBOR as a major type 3, which
   represents a string of Unicode characters that are encoded as UTF-8
   [RFC3629] (see Section 3.1 of [RFC8949]).  Thus, both SWID and CoSWID
   use UTF-8 for the encoding of characters in text strings.

   To ensure that UTF-8 character strings are able to be encoded/decoded
   and exchanged interoperably, text strings in CoSWID MUST be encoded
   in a way that is consistent with the Net-Unicode definition provided
   in [RFC5198].

   All names registered with IANA according to the requirements in
   Section 6.2 also MUST be valid according to the XML Schema NMTOKEN
   data type (see [W3C.REC-xmlschema-2-20041028], Section 3.3.4) to
   ensure compatibility with the SWID specification where these names
   are used.

2.2.  Concise SWID Extensions

   The CoSWID specification contains two features that are not included
   in the SWID specification on which it is based.  These features are:

   *  The explicit definition of types for some attributes in the ISO-
      19770-2:2015 XML representation that are typically represented by
      the any-attribute item in the SWID model.  These are covered in
      Section 2.5.

   *  The inclusion of extension points in the CoSWID specification
      using CDDL sockets (see Section 3.9 of [RFC8610]).  The use of
      CDDL sockets allows for well-formed extensions to be defined in
      supplementary CDDL descriptions that support additional uses of
      CoSWID tags that go beyond the original scope of ISO-19770-2:2015
      tags.

   The following CDDL sockets (extension points) are defined in this
   document; they allow the addition of new information structures to
   their respective CDDL groups.

    +=====================+=================================+=========+
    | Map Name            | CDDL Socket                     | Defined |
    |                     |                                 | in      |
    +=====================+=================================+=========+
    | concise-swid-tag    | $$coswid-extension              | Section |
    |                     |                                 | 2.3     |
    +---------------------+---------------------------------+---------+
    | entity-entry        | $$entity-extension              | Section |
    |                     |                                 | 2.6     |
    +---------------------+---------------------------------+---------+
    | link-entry          | $$link-extension                | Section |
    |                     |                                 | 2.7     |
    +---------------------+---------------------------------+---------+
    | software-meta-entry | $$software-meta-extension       | Section |
    |                     |                                 | 2.8     |
    +---------------------+---------------------------------+---------+
    | resource-collection | $$resource-collection-extension | Section |
    |                     |                                 | 2.9.2   |
    +---------------------+---------------------------------+---------+
    | file-entry          | $$file-extension                | Section |
    |                     |                                 | 2.9.2   |
    +---------------------+---------------------------------+---------+
    | directory-entry     | $$directory-extension           | Section |
    |                     |                                 | 2.9.2   |
    +---------------------+---------------------------------+---------+
    | process-entry       | $$process-extension             | Section |
    |                     |                                 | 2.9.2   |
    +---------------------+---------------------------------+---------+
    | resource-entry      | $$resource-extension            | Section |
    |                     |                                 | 2.9.2   |
    +---------------------+---------------------------------+---------+
    | payload-entry       | $$payload-extension             | Section |
    |                     |                                 | 2.9.3   |
    +---------------------+---------------------------------+---------+
    | evidence-entry      | $$evidence-extension            | Section |
    |                     |                                 | 2.9.4   |
    +---------------------+---------------------------------+---------+

                Table 1: CoSWID CDDL Group Extension Points

   The "CoSWID Items" registry, defined in Section 6.1, provides a
   registration mechanism allowing new items, and their associated index
   values, to be added to the CoSWID model through the use of the CDDL
   sockets described in the table above.  This registration mechanism
   provides for well-known index values for data items in CoSWID
   extensions, allowing these index values to be recognized by
   implementations supporting a given extension.

   The following additional CDDL sockets are defined in this document to
   allow for adding new values to corresponding type choices (i.e., to
   represent enumerations) via custom CDDL specifications.

           +==================+=================+=============+
           | Enumeration Name | CDDL Socket     | Defined in  |
           +==================+=================+=============+
           | version-scheme   | $version-scheme | Section 4.1 |
           +------------------+-----------------+-------------+
           | role             | $role           | Section 4.2 |
           +------------------+-----------------+-------------+
           | ownership        | $ownership      | Section 4.3 |
           +------------------+-----------------+-------------+
           | rel              | $rel            | Section 4.4 |
           +------------------+-----------------+-------------+
           | use              | $use            | Section 4.5 |
           +------------------+-----------------+-------------+

            Table 2: CoSWID CDDL Enumeration Extension Points

   A number of IANA registries for CoSWID values are also defined in
   Section 6.2; these registries allow new values to be registered with
   IANA for the enumerations above.  This registration mechanism
   supports the definition of new well-known index values and names for
   new enumeration values used by CoSWID, which can also be used by
   other software tagging specifications.  This registration mechanism
   allows new standardized enumerated values to be shared between
   multiple tagging specifications (and associated implementations) over
   time.

2.3.  The concise-swid-tag Map

   The CDDL specification for the root concise-swid-tag map is as
   follows.  This rule and its constraints MUST be followed when
   creating or validating a CoSWID tag:

   concise-swid-tag = {
     tag-id => text / bstr .size 16,
     tag-version => integer,
     ? corpus => bool,
     ? patch => bool,
     ? supplemental => bool,
     software-name => text,
     ? software-version => text,
     ? version-scheme => $version-scheme,
     ? media => text,
     ? software-meta => one-or-more<software-meta-entry>,
     entity => one-or-more<entity-entry>,
     ? link => one-or-more<link-entry>,
     ? payload-or-evidence,
     * $$coswid-extension,
     global-attributes,
   }

   payload-or-evidence //= ( payload => payload-entry )
   payload-or-evidence //= ( evidence => evidence-entry )

   tag-id = 0
   software-name = 1
   entity = 2
   evidence = 3
   link = 4
   software-meta = 5
   payload = 6
   corpus = 8
   patch = 9
   media = 10
   supplemental = 11
   tag-version = 12
   software-version = 13
   version-scheme = 14

   $version-scheme /= multipartnumeric
   $version-scheme /= multipartnumeric-suffix
   $version-scheme /= alphanumeric
   $version-scheme /= decimal
   $version-scheme /= semver
   $version-scheme /= int / text
   multipartnumeric = 1
   multipartnumeric-suffix = 2
   alphanumeric = 3
   decimal = 4
   semver = 16384

   The following list describes each member of the concise-swid-tag root
   map.

   global-attributes:  A list of items, including an optional language
      definition to support the processing of text-string values and an
      unbounded set of any-attribute items.  Described in Section 2.5.

   tag-id (index 0):  A 16-byte binary string, or a textual identifier,
      uniquely referencing a software component.  The tag identifier
      MUST be globally unique.  Failure to ensure global uniqueness can
      create ambiguity in tag use, since the tag-id serves as the global
      key for matching and lookups.  If represented as a 16-byte binary
      string, the identifier MUST be a valid Universally Unique
      Identifier (UUID) as defined by [RFC4122].  There are no strict
      guidelines on how the identifier is structured, but examples
      include a 16-byte Globally Unique Identifier (GUID) (e.g., class 4
      UUID) [RFC4122], or a DNS domain name followed by a "/" and a text
      string, where the domain name serves to ensure uniqueness across
      organizations.  A textual tag-id value MUST NOT contain a sequence
      of two underscores ("__").  This is because a sequence of two
      underscores is used to separate the TAG_CREATOR_REGID value and
      UNIQUE_ID value in a Software Identifier and a sequence of two
      underscores in a tag-id value could create ambiguity when parsing
      this identifier.  See Section 6.7.

   software-name (index 1):  A textual item that provides the software
      component's name.  This name is likely the same name that would
      appear in a package management tool.  This item maps to
      '/SoftwareIdentity/@name' in [SWID].

   entity (index 2):  Provides information about one or more
      organizations responsible for producing the CoSWID tag, and
      producing or releasing the software component referenced by this
      CoSWID tag.  Described in Section 2.6.

   evidence (index 3):  Can be used to record the results of a software
      discovery process used to identify untagged software on an
      endpoint or to represent indicators for why software is believed
      to be installed on the endpoint.  In either case, a CoSWID tag can
      be created by the tool performing an analysis of the software
      components installed on the endpoint.  This item is mutually
      exclusive to payload, as evidence is always generated on the
      target device ad hoc.  Described in Section 2.9.4.

   link (index 4):  Provides a means to establish relationship arcs
      between the tag and another item.  A given link can be used to
      establish the relationship between tags or to reference another
      resource that is related to the CoSWID tag, e.g., vulnerability
      database association, Resource-Oriented Lightweight Information
      Exchange (ROLIE) Feed [RFC8322], Manufacturer Usage Description
      (MUD) resource [RFC8520], software download location, etc.).  This
      is modeled after the HTML "link" element.  Described in
      Section 2.7.

   software-meta (index 5):  An open-ended map of key/value data pairs.
      A number of predefined keys can be used within this item providing
      for common usage and semantics across the industry.  The use of
      this map allows any additional attribute to be included in the
      tag.  It is expected that industry groups will use a common set of
      attribute names to allow for interoperability within their
      communities.  Described in Section 2.8.  This item maps to
      '/SoftwareIdentity/Meta' in [SWID].

   payload (index 6):  Represents a collection of software artifacts
      (described by child items) that compose the target software.  For
      example, these artifacts could be the files included with an
      installer for a corpus tag or installed on an endpoint when the
      software component is installed for a primary or patch tag.  The
      artifacts listed in a payload may be a superset of the software
      artifacts that are actually installed.  Based on user selections
      at install time, an installation might not include every artifact
      that could be created or executed on the endpoint when the
      software component is installed or run.  This item is mutually
      exclusive to evidence, as payload can only be provided by an
      external entity.  Described in Section 2.9.3.

   corpus (index 8):  A boolean value that indicates if the tag
      identifies and describes an installable software component in its
      pre-installation state.  Installable software includes an
      installation package or installer for a software component, a
      software update, or a patch.  If the CoSWID tag represents
      installable software, the corpus item MUST be set to "true".  If
      not provided, the default value MUST be considered "false".

   patch (index 9):  A boolean value that indicates if the tag
      identifies and describes an installed patch that has made
      incremental changes to a software component installed on an
      endpoint.  If a CoSWID tag is for a patch, the patch item MUST be
      set to "true".  If not provided, the default value MUST be
      considered "false".  A patch item's value MUST NOT be set to
      "true" if the installation of the associated software package
      changes the version of a software component.

   media (index 10):  A text value that provides a hint to the tag
      consumer to understand what target platform this tag applies to.
      This item MUST be formatted as a query as defined by the W3C
      "Media Queries Level 3" Recommendation (see
      [W3C.REC-mediaqueries-3-20220405]).  Support for media queries is
      included here for interoperability with [SWID], which does not
      provide any further requirements for media query use.  Thus, this
      specification does not clarify how a media query is to be used for
      a CoSWID.

   supplemental (index 11):  A boolean value that indicates if the tag
      is providing additional information to be associated with another
      referenced SWID or CoSWID tag.  This allows tools and users to
      record their own metadata about a software component without
      modifying SWID primary or patch tags created by a software
      provider.  If a CoSWID tag is a supplemental tag, the supplemental
      item MUST be set to "true".  If not provided, the default value
      MUST be considered "false".

   tag-version (index 12):  An integer value that indicates the specific
      release revision of the tag.  Typically, the initial value of this
      field is set to 0 and the value is increased for subsequent tags
      produced for the same software component release.  This value
      allows a CoSWID tag producer to correct an incorrect tag
      previously released without indicating a change to the underlying
      software component the tag represents.  For example, the tag-
      version could be changed to add new metadata, to correct a broken
      link, to add a missing payload entry, etc.  When producing a
      revised tag, the new tag-version value MUST be greater than the
      old tag-version value.

   software-version (index 13):  A textual value representing the
      specific release or development version of the software component.
      This item maps to '/SoftwareIdentity/@version' in [SWID].

   version-scheme (index 14):  An integer or textual value representing
      the versioning scheme used for the software-version item, as an
      integer label with text escape.  For the "Version Scheme" values,
      see Section 4.1.  If an integer value is used, it MUST be an index
      value in the range -256 to 65535.  Integer values in the range
      -256 to -1 are reserved for testing and use in closed environments
      (see Section 6.2.2).  Integer values in the range 0 to 65535
      correspond to registered entries in the IANA "Software ID Version
      Scheme Values" registry (see Section 6.2.4).

   $$coswid-extension:  A CDDL socket that is used to add new
      information structures to the concise-swid-tag root map.  See
      Section 2.2.

2.4.  concise-swid-tag Co-constraints

   The following co-constraints apply to the information provided in the
   concise-swid-tag group.

   *  The patch and supplemental items MUST NOT both be set to "true".

   *  If the patch item is set to "true", the tag MUST contain at least
      one link item (see Section 2.7) with both the rel item value of
      "patches" and an href item specifying an association with the
      software that was patched.  Without at least one link item, the
      target of the patch cannot be identified and the patch tag cannot
      be applied without external context.

   *  If all of the corpus, patch, and supplemental items are "false" or
      if the corpus item is set to "true", then a software-version item
      MUST be included with a value set to the version of the software
      component.

2.5.  The global-attributes Group

   The global-attributes group provides a list of items, including an
   optional language definition to support the processing of text-string
   values, and an unbounded set of any-attribute items allowing for
   additional items to be provided as a general point of extension in
   the model.

   The CDDL for the global-attributes group follows:

   global-attributes = (
     ? lang => text,
     * any-attribute,
   )

   any-attribute = (
     label => one-or-more<text> / one-or-more<int>
   )

   label = text / int

   The following list describes each child item of this group.

   lang (index 15):  A textual language tag that conforms with the IANA
      "Language Subtag Registry" [RFC5646].  The context of the
      specified language applies to all sibling and descendant textual
      values, unless a descendant object has defined a different
      language tag.  Thus, a new context is established when a
      descendant object redefines a new language tag.  All textual
      values within a given context MUST be considered expressed in the
      specified language.

   any-attribute:  A sub-group that provides a means to include
      arbitrary information via label/index ("key") value pairs.  Labels
      can be either a single integer or text string.  Values can be a
      single integer, a text string, or an array of integers or text
      strings.

2.6.  The entity-entry Map

   The CDDL for the entity-entry map follows:

   entity-entry = {
     entity-name => text,
     ? reg-id => any-uri,
     role => one-or-more<$role>,
     ? thumbprint => hash-entry,
     * $$entity-extension,
     global-attributes,
   }

   entity-name = 31
   reg-id = 32
   role = 33
   thumbprint = 34

   $role /= tag-creator
   $role /= software-creator
   $role /= aggregator
   $role /= distributor
   $role /= licensor
   $role /= maintainer
   $role /= int / text
   tag-creator=1
   software-creator=2
   aggregator=3
   distributor=4
   licensor=5
   maintainer=6

   The following list describes each child item of this group.

   global-attributes:  The global-attributes group as described in
      Section 2.5.

   entity-name (index 31):  The textual name of the organizational
      entity claiming the roles specified by the role item for the
      CoSWID tag.  This item maps to '/SoftwareIdentity/Entity/@name' in
      [SWID].

   reg-id (index 32):  Registration ID.  This value is intended to
      uniquely identify a naming authority in a given scope (e.g.,
      global, organization, vendor, customer, administrative domain,
      etc.) for the referenced entity.  The value of a registration ID
      MUST be a URI as defined in [RFC3986]; it is not intended to be
      dereferenced.  The scope will usually be the scope of an
      organization.

   role (index 33):  An integer or textual value (integer label with
      text escape; see Section 2) representing the relationship(s)
      between the entity and this tag or the referenced software
      component.  If an integer value is used, it MUST be an index value
      in the range -256 to 255.  Integer values in the range -256 to -1
      are reserved for testing and use in closed environments (see
      Section 6.2.2).  Integer values in the range 0 to 255 correspond
      to registered entries in the IANA "Software ID Entity Role Values"
      registry (see Section 6.2.5).

      The following additional requirements exist for the use of the
      role item:

      *  An entity item MUST be provided with the role of "tag-creator"
         for every CoSWID tag.  This indicates the organization that
         created the CoSWID tag.

      *  An entity item SHOULD be provided with the role of "software-
         creator" for every CoSWID tag, if this information is known to
         the tag creator.  This indicates the organization that created
         the referenced software component.

   thumbprint (index 34):  Value that provides a hash (i.e., the
      thumbprint) of the signing entity's public key certificate.  This
      item provides an indicator of which entity signed the CoSWID tag,
      which will typically be the tag creator.  See Section 2.9.1 for
      more details on the use of the hash-entry data structure.

   $$entity-extension:  A CDDL socket that can be used to extend the
      entity-entry group model.  See Section 2.2.

2.7.  The link-entry Map

   The CDDL for the link-entry map follows:

   link-entry = {
     ? artifact => text,
     href => any-uri,
     ? media => text,
     ? ownership => $ownership,
     rel => $rel,
     ? media-type => text,
     ? use => $use,
     * $$link-extension,
     global-attributes,
   }

   media = 10
   artifact = 37
   href = 38
   ownership = 39
   rel = 40
   media-type = 41
   use = 42

   $ownership /= shared
   $ownership /= private
   $ownership /= abandon
   $ownership /= int / text
   abandon=1
   private=2
   shared=3

   $rel /= ancestor
   $rel /= component
   $rel /= feature
   $rel /= installationmedia
   $rel /= packageinstaller
   $rel /= parent
   $rel /= patches
   $rel /= requires
   $rel /= see-also
   $rel /= supersedes
   $rel /= supplemental
   $rel /= -256..65536 / text
   ancestor=1
   component=2
   feature=3
   installationmedia=4
   packageinstaller=5
   parent=6
   patches=7
   requires=8
   see-also=9
   supersedes=10
   supplemental=11

   $use /= optional
   $use /= required
   $use /= recommended
   $use /= int / text
   optional=1
   required=2
   recommended=3

   The following list describes each member of this map.

   global-attributes:  The global-attributes group as described in
      Section 2.5.

   media (index 10):  A value that provides a hint to the consumer of
      the link so that the consumer understands what target platform the
      link is applicable to.  This item represents a query as defined by
      the W3C "Media Queries Level 3" Recommendation (see
      [W3C.REC-mediaqueries-3-20220405]).  As highlighted in the
      definition of the media item provided in Section 2.3, support for
      media queries is included here for interoperability with [SWID],
      which does not provide any further requirements for media query
      use.  Thus, this specification does not clarify how a media query
      is to be used for a CoSWID.

   artifact (index 37):  To be used with rel="installationmedia".  This
      item's value provides the absolute filesystem path to the
      installer executable or script that can be run to launch the
      referenced installation.  Links with the same artifact name MUST
      be considered mirrors of each other, allowing the installation
      media to be acquired from any of the described sources.

   href (index 38):  A URI-reference [RFC3986] for the referenced
      resource.  The href item's value can be, but is not limited to,
      the following (which is a slightly modified excerpt from [SWID]):

      *  If no URI scheme is provided, then the URI-reference is a
         relative reference to the base URI of the CoSWID tag, i.e., the
         URI under which the CoSWID tag was provided -- for example,
         "./folder/supplemental.coswid".

      *  This item can be a physical resource location with any
         acceptable URI scheme (e.g., <file://>, <http://>, <https://>,
         <ftp://>).

      *  A URI-like expression with "swid:" as the scheme refers to
         another SWID or CoSWID by the referenced tag's tag-id.  This
         expression needs to be resolved in the context of the endpoint
         by software that can look up other SWID or CoSWID tags.  For
         example, "swid:2df9de35-0aff-4a86-ace6-f7dddd1ade4c" references
         the tag with the tag-id value "2df9de35-0aff-
         4a86-ace6-f7dddd1ade4c".  See Section 5.1 for guidance on the
         "swid" expressions.

      *  This item can be a URI-like expression with "swidpath:" as the
         scheme, which refers to another software tag via an XPath query
         [W3C.REC-xpath20-20101214] that matches items in that tag
         (Section 5.2).  This scheme is provided for compatibility with
         [SWID].  This specification does not define how to resolve an
         XPath query in the context of CBOR.  See Section 5.2 for
         guidance on the "swidpath" expressions.

   ownership (index 39):  An integer or textual value (integer label
      with text escape; see Section 2).  See Section 4.3 for the list of
      values available for this item.  This item is used when the href
      item references another software component to indicate the degree
      of ownership between the software component referenced by the
      CoSWID tag and the software component referenced by the link.  If
      an integer value is used, it MUST be an index value in the range
      -256 to 255.  Integer values in the range -256 to -1 are reserved
      for testing and use in closed environments (see Section 6.2.2).
      Integer values in the range 0 to 255 correspond to registered
      entries in the "Software ID Link Ownership Values" registry.

   rel (index 40):  An integer or textual value (integer label with text
      escape; see Section 2).  See Section 4.4 for the list of values
      available for this item.  This item identifies the relationship
      between this CoSWID and the target resource identified by the href
      item.  If an integer value is used, it MUST be an index value in
      the range -256 to 65535.  Integer values in the range -256 to -1
      are reserved for testing and use in closed environments (see
      Section 6.2.2).  Integer values in the range 0 to 65535 correspond
      to registered entries in the IANA "Software ID Link Relationship
      Values" registry (see Section 6.2.7).  If a string value is used,
      it MUST be either a private use name as defined in Section 6.2.2
      or a "Relation Name" from the IANA "Link Relation Types" registry
      (see <https://www.iana.org/assignments/link-relations/>) as
      defined by [RFC8288].  When a string value defined in the IANA
      "Software ID Link Relationship Values" registry matches a Relation
      Name defined in the IANA "Link Relation Types" registry, the index
      value in the IANA "Software ID Link Relationship Values" registry
      MUST be used instead, as this relationship has a specialized
      meaning in the context of a CoSWID tag.  String values correspond
      to registered entries in the "Software ID Link Relationship
      Values" registry.

   media-type (index 41):  Supplies the resource consumer with a hint
      regarding what type of resource to expect.  A link can point to
      arbitrary resources on the endpoint, local network, or Internet
      using the href item.  (This is a _hint_: there is no obligation
      for the server hosting the target of the URI to use the indicated
      media type when the URI is dereferenced.)  Media types are
      identified by referencing a "Name" from the IANA "Media Types"
      registry (see <https://www.iana.org/assignments/media-types/>).
      This item maps to '/SoftwareIdentity/Link/@type' in [SWID].

   use (index 42):  An integer or textual value (integer label with text
      escape; see Section 2).  See Section 4.5 for the list of values
      available for this item.  This item is used to determine if the
      referenced software component has to be installed before
      installing the software component identified by the CoSWID tag.
      If an integer value is used, it MUST be an index value in the
      range -256 to 255.  Integer values in the range -256 to -1 are
      reserved for testing and use in closed environments (see
      Section 6.2.2).  Integer values in the range 0 to 255 correspond
      to registered entries in the IANA "Software ID Link Use Values"
      registry (see Section 6.2.8).  If a string value is used, it MUST
      be a private use name as defined in Section 6.2.2.  String values
      correspond to registered entries in the "Software ID Link Use
      Values" registry.

   $$link-extension:  A CDDL socket that can be used to extend the link-
      entry map model.  See Section 2.2.

2.8.  The software-meta-entry Map

   The CDDL for the software-meta-entry map follows:

   software-meta-entry = {
     ? activation-status => text,
     ? channel-type => text,
     ? colloquial-version => text,
     ? description => text,
     ? edition => text,
     ? entitlement-data-required => bool,
     ? entitlement-key => text,
     ? generator => text / bstr .size 16,
     ? persistent-id => text,
     ? product => text,
     ? product-family => text,
     ? revision => text,
     ? summary => text,
     ? unspsc-code => text,
     ? unspsc-version => text,
     * $$software-meta-extension,
     global-attributes,
   }

   activation-status = 43
   channel-type = 44
   colloquial-version = 45
   description = 46
   edition = 47
   entitlement-data-required = 48
   entitlement-key = 49
   generator = 50
   persistent-id = 51
   product = 52
   product-family = 53
   revision = 54
   summary = 55
   unspsc-code = 56
   unspsc-version = 57

   The following list describes each child item of this group.

   global-attributes:  The global-attributes group as described in
      Section 2.5.

   activation-status (index 43):  A textual value that identifies how
      the software component has been activated, which might relate to
      specific terms and conditions for its use (e.g., trial,
      serialized, licensed, unlicensed, etc.) and relate to an
      entitlement.  This attribute is typically used in supplemental
      tags, as it contains information that might be selected during a
      specific install.

   channel-type (index 44):  A textual value that identifies which
      sales, licensing, or marketing channel the software component has
      been targeted for (e.g., volume, retail, original equipment
      manufacturer (OEM), academic, etc.).  This attribute is typically
      used in supplemental tags, as it contains information that might
      be selected during a specific install.

   colloquial-version (index 45):  A textual value for the software
      component's informal or colloquial version.  Examples may include
      a year value, a major version number, or a similar value used to
      identify a group of specific software component releases that are
      part of the same release/support cycle.  This version can be the
      same through multiple releases of a software component, while the
      software-version specified in the concise-swid-tag group is much
      more specific and will change for each software component release.
      This version is intended to be used for string comparison (byte by
      byte) only and is not intended to be used to determine if a
      specific value is earlier or later in a sequence.

   description (index 46):  A textual value that provides a detailed
      description of the software component.  This value MAY be multiple
      paragraphs separated by CR LF characters as described by
      [RFC5198].

   edition (index 47):  A textual value indicating that the software
      component represents a functional variation of the code base used
      to support multiple software components.  For example, this item
      can be used to differentiate enterprise, standard, or professional
      variants of a software component.

   entitlement-data-required (index 48):  A boolean value that can be
      used to determine if accompanying proof of entitlement is needed
      when a software license reconciliation process is performed.

   entitlement-key (index 49):  A vendor-specific textual key that can
      be used to identify and establish a relationship to an
      entitlement.  Examples of an entitlement-key might include a
      serial number, product key, or license key.  For values that
      relate to a given software component install (e.g., license key),
      a supplemental tag will typically contain this information.  In
      other cases, where a general-purpose key can be provided that
      applies to all possible installs of the software component on
      different endpoints, a primary tag will typically contain this
      information.  Since CoSWID tags are not intended to contain
      confidential information, tag authors are advised not to record
      unprotected, private software license keys in this field.

   generator (index 50):  The name (or tag-id) of the software component
      that created the CoSWID tag.  If the generating software component
      has a SWID or CoSWID tag, then the tag-id for the generating
      software component SHOULD be provided.

   persistent-id (index 51):  A globally unique identifier used to
      identify a set of software components that are related.  Software
      components sharing the same persistent-id can be different
      versions.  This item can be used to relate software components,
      released at different points in time or through different release
      channels, that may not be able to be related through the use of
      the link item.

   product (index 52):  A basic name for the software component that can
      be common across multiple tagged software components (e.g., Apache
      HTTP daemon (HTTPD)).

   product-family (index 53):  A textual value indicating the software
      components' overall product family.  This should be used when
      multiple related software components form a larger capability that
      is installed on multiple different endpoints.  For example, some
      software families may consist of a server, a client, and shared
      service components that are part of a larger capability.  Email
      systems, enterprise applications, backup services, web
      conferencing, and similar capabilities are examples of families.
      The use of this item is not intended to represent groups of
      software that are bundled or installed together.  The persistent-
      id or link items SHOULD be used to relate bundled software
      components.

   revision (index 54):  A string value indicating an informal or
      colloquial release version of the software.  This value can
      provide a different version value as compared to the software-
      version specified in the concise-swid-tag group.  This is useful
      when one or more releases need to have an informal version label
      that differs from the specific exact version value specified by
      software-version.  Examples can include SP1, RC1, Beta, etc.

   summary (index 55):  A short description of the software component.
      This MUST be a single sentence suitable for display in a user
      interface.

   unspsc-code (index 56):  An 8-digit United Nations Standard Products
      and Services Code (UNSPSC) classification code for the software
      component as defined by the UNSPSC [UNSPSC].

   unspsc-version (index 57):  The UNSPSC version used to define the
      unspsc-code value.

   $$software-meta-extension:  A CDDL socket that can be used to extend
      the software-meta-entry group model.  See Section 2.2.

2.9.  The Resource Collection Definition

2.9.1.  The hash-entry Array

   CoSWID adds explicit support for the representation of hash entries
   using algorithms that are registered in the IANA "Named Information
   Hash Algorithm Registry" [IANA.named-information].  This array is
   used by both the hash (index 7) and thumbprint (index 34) values.
   This is the equivalent of the namespace qualified "hash" attribute in
   [SWID].

   hash-entry = [
     hash-alg-id: int,
     hash-value: bytes,
   ]

   The number used as a value for hash-alg-id is an integer-based hash
   algorithm identifier whose value MUST refer to an ID in the IANA
   "Named Information Hash Algorithm Registry" [IANA.named-information]
   with a Status of "current" (at the time the generator software was
   built or later); other hash algorithms MUST NOT be used.  If the
   hash-alg-id is not known, then the integer value "0" MUST be used.
   This allows for conversion from ISO SWID tags [SWID], which do not
   allow an algorithm to be identified for this field.

   The hash-value MUST represent the raw hash value as a byte string (as
   opposed to, for example, base64 encoded) generated from the
   representation of the resource using the hash algorithm indicated by
   hash-alg-id.

2.9.2.  The resource-collection Group

   The resource-collection group provides a list of items used in both
   evidence (created by a software discovery process) and payload
   (installed in an endpoint) content of a CoSWID tag document to
   structure and differentiate the content of specific CoSWID tag types.
   Potential content includes directories, files, processes, or
   resources.

   The CDDL for the resource-collection group follows:

   path-elements-group = ( ? directory => one-or-more<directory-entry>,
                           ? file => one-or-more<file-entry>,
                         )

   resource-collection = (
     path-elements-group,
     ? process => one-or-more<process-entry>,
     ? resource => one-or-more<resource-entry>,
     * $$resource-collection-extension,
   )

   filesystem-item = (
     ? key => bool,
     ? location => text,
     fs-name => text,
     ? root => text,
   )

   file-entry = {
     filesystem-item,
     ? size => uint,
     ? file-version => text,
     ? hash => hash-entry,
     * $$file-extension,
     global-attributes,
   }

   directory-entry = {
     filesystem-item,
     ? path-elements => { path-elements-group },
     * $$directory-extension,
     global-attributes,
   }

   process-entry = {
     process-name => text,
     ? pid => integer,
     * $$process-extension,
     global-attributes,
   }

   resource-entry = {
     type => text,
     * $$resource-extension,
     global-attributes,
   }

   hash = 7
   directory = 16
   file = 17
   process = 18
   resource = 19
   size = 20
   file-version = 21
   key = 22
   location = 23
   fs-name = 24
   root = 25
   path-elements = 26
   process-name = 27
   pid = 28
   type = 29

   The following list describes each member of the groups and maps
   illustrated above.

   filesystem-item:  A list of common items used for representing the
      filesystem root, relative location, name, and significance of a
      file or directory item.

   global-attributes:  The global-attributes group as described in
      Section 2.5.

   hash (index 7):  Value that provides a hash of a file.  This item
      provides an integrity measurement with respect to a specific file.
      See Section 2.9.1 for more details on the use of the hash-entry
      data structure.

   directory (index 16):  Item that allows child directory and file
      items to be defined within a directory hierarchy for the software
      component.

   file (index 17):  Item that allows details about a file to be
      provided for the software component.

   process (index 18):  Item that allows details to be provided about
      the runtime behavior of the software component, such as
      information that will appear in a process listing on an endpoint.

   resource (index 19):  Item that can be used to provide details about
      an artifact or capability expected to be found on an endpoint or
      evidence collected related to the software component.  This can be
      used to represent concepts not addressed directly by the
      directory, file, or process items.  Examples include registry
      keys, bound ports, etc.  The equivalent construct in [SWID] is
      currently underspecified.  As a result, this item might be further
      defined through extensions in the future.

   size (index 20):  The file's size in bytes.

   file-version (index 21):  The file's version as reported by querying
      information on the file from the operating system (if available).
      This item maps to
      '/SoftwareIdentity/(Payload|Evidence)/File/@version' in [SWID].

   key (index 22):  A boolean value indicating if a file or directory is
      significant or required for the software component to execute or
      function properly.  These are files or directories that can be
      used to affirmatively determine if the software component is
      installed on an endpoint.

   location (index 23):  The filesystem path where a file is expected to
      be located when installed or copied.  The location MUST be either
      an absolute path, a path relative to the path value included in
      the parent directory item (preferred), or a path relative to the
      location of the CoSWID tag if no parent is defined.  The location
      MUST NOT include a file's name, which is provided by the fs-name
      item.

   fs-name (index 24):  The name of the directory or file without any
      path information.  This aligns with a file "name" in [SWID].  This
      item maps to
      '/SoftwareIdentity/(Payload|Evidence)/(File|Directory)/@name' in
      [SWID].

   root (index 25):  A host-specific name for the root of the
      filesystem.  The location item is considered relative to this
      location if specified.  If not provided, the value provided by the
      location item is expected to be relative to its parent or the
      location of the CoSWID tag if no parent is provided.

   path-elements (index 26):  Group that allows a hierarchy of directory
      and file items to be defined in payload or evidence items.  This
      is a construction within the CDDL definition of CoSWID to support
      shared syntax and does not appear in [SWID].

   process-name (index 27):  The software component's process name as it
      will appear in an endpoint's process list.  This aligns with a
      process "name" in [SWID].  This item maps to
      '/SoftwareIdentity/(Payload|Evidence)/Process/@name' in [SWID].

   pid (index 28):  The process ID identified for a running instance of
      the software component in the endpoint's process list.  This is
      used as part of the evidence item.

   type (index 29):  A human-readable string indicating the type of
      resource.

   $$resource-collection-extension:  A CDDL socket that can be used to
      extend the resource-collection group model.  This can be used to
      add new specialized types of resources.  See Section 2.2.

   $$file-extension:  A CDDL socket that can be used to extend the file-
      entry group model.  See Section 2.2.

   $$directory-extension:  A CDDL socket that can be used to extend the
      directory-entry group model.  See Section 2.2.

   $$process-extension:  A CDDL socket that can be used to extend the
      process-entry group model.  See Section 2.2.

   $$resource-extension:  A CDDL socket that can be used to extend the
      resource-entry group model.  See Section 2.2.

2.9.3.  The payload-entry Map

   The CDDL for the payload-entry map follows:

   payload-entry = {
     resource-collection,
     * $$payload-extension,
     global-attributes,
   }

   The following list describes each child item of this group.

   global-attributes:  The global-attributes group as described in
      Section 2.5.

   resource-collection:  The resource-collection group as described in
      Section 2.9.2.

   $$payload-extension:  A CDDL socket that can be used to extend the
      payload-entry group model.  See Section 2.2.

2.9.4.  The evidence-entry Map

   The CDDL for the evidence-entry map follows:

   evidence-entry = {
     resource-collection,
     ? date => integer-time,
     ? device-id => text,
     ? location => text,
     * $$evidence-extension,
     global-attributes,
   }

   date = 35
   device-id = 36

   The following list describes each child item of this group.

   global-attributes:  The global-attributes group as described in
      Section 2.5.

   resource-collection:  The resource-collection group as described in
      Section 2.9.2.

   location (index 23):  The filesystem path of the location of the
      CoSWID tag generated as evidence.  This path is always an absolute
      file path (unlike the value of a location item found within a
      filesystem-item as described in Section 2.9.2, which can be either
      a relative path or an absolute path).

   date (index 35):  The date and time the information was collected
      pertaining to the evidence item in epoch-based date/time format as
      specified in Section 3.4.2 of [RFC8949].

   device-id (index 36):  The endpoint's string identifier from which
      the evidence was collected.

   $$evidence-extension:  A CDDL socket that can be used to extend the
      evidence-entry group model.  See Section 2.2.

2.10.  Full CDDL Specification

   In order to create a valid CoSWID document, the structure of the
   corresponding CBOR message MUST adhere to the following CDDL
   specification.

   <CODE BEGINS> file "concise-swid-tag.cddl"
   concise-swid-tag = {
     tag-id => text / bstr .size 16,
     tag-version => integer,
     ? corpus => bool,
     ? patch => bool,
     ? supplemental => bool,
     software-name => text,
     ? software-version => text,
     ? version-scheme => $version-scheme,
     ? media => text,
     ? software-meta => one-or-more<software-meta-entry>,
     entity => one-or-more<entity-entry>,
     ? link => one-or-more<link-entry>,
     ? payload-or-evidence,
     * $$coswid-extension,
     global-attributes,
   }

   payload-or-evidence //= ( payload => payload-entry )
   payload-or-evidence //= ( evidence => evidence-entry )

   any-uri = uri
   label = text / int

   $version-scheme /= multipartnumeric
   $version-scheme /= multipartnumeric-suffix
   $version-scheme /= alphanumeric
   $version-scheme /= decimal
   $version-scheme /= semver
   $version-scheme /= int / text

   any-attribute = (
     label => one-or-more<text> / one-or-more<int>
   )

   one-or-more<T> = T / [ 2* T ]

   global-attributes = (
     ? lang => text,
     * any-attribute,
   )

   hash-entry = [
     hash-alg-id: int,
     hash-value: bytes,
   ]

   entity-entry = {
     entity-name => text,
     ? reg-id => any-uri,
     role => one-or-more<$role>,
     ? thumbprint => hash-entry,
     * $$entity-extension,
     global-attributes,
   }

   $role /= tag-creator
   $role /= software-creator
   $role /= aggregator
   $role /= distributor
   $role /= licensor
   $role /= maintainer
   $role /= int / text

   link-entry = {
     ? artifact => text,
     href => any-uri,
     ? media => text,
     ? ownership => $ownership,
     rel => $rel,
     ? media-type => text,
     ? use => $use,
     * $$link-extension,
     global-attributes,
   }

   $ownership /= shared
   $ownership /= private
   $ownership /= abandon
   $ownership /= int / text

   $rel /= ancestor
   $rel /= component
   $rel /= feature
   $rel /= installationmedia
   $rel /= packageinstaller
   $rel /= parent
   $rel /= patches
   $rel /= requires
   $rel /= see-also
   $rel /= supersedes
   $rel /= supplemental
   $rel /= -256..65536 / text

   $use /= optional
   $use /= required
   $use /= recommended
   $use /= int / text

   software-meta-entry = {
     ? activation-status => text,
     ? channel-type => text,
     ? colloquial-version => text,
     ? description => text,
     ? edition => text,
     ? entitlement-data-required => bool,
     ? entitlement-key => text,
     ? generator => text / bstr .size 16,
     ? persistent-id => text,
     ? product => text,
     ? product-family => text,
     ? revision => text,
     ? summary => text,
     ? unspsc-code => text,
     ? unspsc-version => text,
     * $$software-meta-extension,
     global-attributes,
   }

   path-elements-group = ( ? directory => one-or-more<directory-entry>,
                           ? file => one-or-more<file-entry>,
                         )

   resource-collection = (
     path-elements-group,
     ? process => one-or-more<process-entry>,
     ? resource => one-or-more<resource-entry>,
     * $$resource-collection-extension,
   )

   file-entry = {
     filesystem-item,
     ? size => uint,
     ? file-version => text,
     ? hash => hash-entry,
     * $$file-extension,
     global-attributes,
   }

   directory-entry = {
     filesystem-item,
     ? path-elements => { path-elements-group },
     * $$directory-extension,
     global-attributes,
   }

   process-entry = {
     process-name => text,
     ? pid => integer,
     * $$process-extension,
     global-attributes,
   }

   resource-entry = {
     type => text,
     * $$resource-extension,
     global-attributes,
   }

   filesystem-item = (
     ? key => bool,
     ? location => text,
     fs-name => text,
     ? root => text,
   )

   payload-entry = {
     resource-collection,
     * $$payload-extension,
     global-attributes,
   }

   evidence-entry = {
     resource-collection,
     ? date => integer-time,
     ? device-id => text,
     ? location => text,
     * $$evidence-extension,
     global-attributes,
   }

   integer-time = #6.1(int)

   ; "global map member" integer indices
   tag-id = 0
   software-name = 1
   entity = 2
   evidence = 3
   link = 4
   software-meta = 5
   payload = 6
   hash = 7
   corpus = 8
   patch = 9
   media = 10
   supplemental = 11
   tag-version = 12
   software-version = 13
   version-scheme = 14
   lang = 15
   directory = 16
   file = 17
   process = 18
   resource = 19
   size = 20
   file-version = 21
   key = 22
   location = 23
   fs-name = 24
   root = 25
   path-elements = 26
   process-name = 27
   pid = 28
   type = 29
   entity-name = 31
   reg-id = 32
   role = 33
   thumbprint = 34
   date = 35
   device-id = 36
   artifact = 37
   href = 38
   ownership = 39
   rel = 40
   media-type = 41
   use = 42
   activation-status = 43
   channel-type = 44
   colloquial-version = 45
   description = 46
   edition = 47
   entitlement-data-required = 48
   entitlement-key = 49
   generator = 50
   persistent-id = 51
   product = 52
   product-family = 53
   revision = 54
   summary = 55
   unspsc-code = 56
   unspsc-version = 57

   ; "version-scheme" integer indices
   multipartnumeric = 1
   multipartnumeric-suffix = 2
   alphanumeric = 3
   decimal = 4
   semver = 16384

   ; "role" integer indices
   tag-creator=1
   software-creator=2
   aggregator=3
   distributor=4
   licensor=5
   maintainer=6

   ; "ownership" integer indices
   abandon=1
   private=2
   shared=3

   ; "rel" integer indices
   ancestor=1
   component=2
   feature=3
   installationmedia=4
   packageinstaller=5
   parent=6
   patches=7
   requires=8
   see-also=9
   supersedes=10
   ; supplemental=11 ; already defined

   ; "use" integer indices
   optional=1
   required=2
   recommended=3
   <CODE ENDS>

3.  Determining the Type of CoSWID

   The operational model for SWID and CoSWID tags was introduced in
   Section 1.1, which described four different CoSWID tag types.  The
   following additional rules apply to the use of CoSWID tags to ensure
   that created tags properly identify the tag type.

   The first matching rule MUST determine the type of the CoSWID tag.

   Primary Tag:  A CoSWID tag MUST be considered a primary tag if the
      corpus, patch, and supplemental items are "false".

   Supplemental Tag:  A CoSWID tag MUST be considered a supplemental tag
      if the supplemental item is set to "true".

   Corpus Tag:  A CoSWID tag MUST be considered a corpus tag if the
      corpus item is "true".

   Patch Tag:  A CoSWID tag MUST be considered a patch tag if the patch
      item is "true".

      |  Note: It is possible for some or all of the corpus, patch, and
      |  supplemental items to simultaneously have values set as "true".
      |  The rules above provide a means to determine the tag's type in
      |  such a case.  For example, a SWID or CoSWID tag for a patch
      |  installer might have both corpus and patch items set to "true".
      |  In such a case, the tag is a "corpus tag".  The tag installed
      |  by this installer would have only the patch item set to "true",
      |  making the installed tag type a "patch tag".

4.  CoSWID Indexed Label Values

   This section defines multiple kinds of indexed label values that are
   maintained in several IANA registries.  See Section 6 for details.
   These values are represented as positive integers.  In each registry,
   the value 0 is marked as Reserved.

4.1.  Version Scheme

   The following table contains a set of values for use in the concise-
   swid-tag group's version-scheme item.  The "Index" value indicates
   the value to use as the version-scheme item's value.  Strings in the
   "Version Scheme Name" column provide human-readable text for the
   value and match the version schemes defined in the ISO/IEC
   19770-2:2015 specification [SWID].  The "Definition" column describes
   the syntax of allowed values for each entry.

    +=======+=========================+===============================+
    | Index | Version Scheme Name     | Definition                    |
    +=======+=========================+===============================+
    | 1     | multipartnumeric        | Numbers separated by dots,    |
    |       |                         | where the numbers are         |
    |       |                         | interpreted as decimal        |
    |       |                         | integers (e.g., 1.2.3,        |
    |       |                         | 1.2.3.4.5.6.7, 1.4.5, 1.21)   |
    +-------+-------------------------+-------------------------------+
    | 2     | multipartnumeric+suffix | Numbers separated by dots,    |
    |       |                         | where the numbers are         |
    |       |                         | interpreted as decimal        |
    |       |                         | integers with an additional   |
    |       |                         | textual suffix (e.g., 1.2.3a) |
    +-------+-------------------------+-------------------------------+
    | 3     | alphanumeric            | Strictly a string, no         |
    |       |                         | interpretation as number      |
    +-------+-------------------------+-------------------------------+
    | 4     | decimal                 | A single decimal floating-    |
    |       |                         | point number                  |
    +-------+-------------------------+-------------------------------+
    | 16384 | semver                  | A semantic version as defined |
    |       |                         | by [SWID].  Also see the      |
    |       |                         | [SEMVER] specification for    |
    |       |                         | more information              |
    +-------+-------------------------+-------------------------------+

                       Table 3: Version Scheme Values

   "multipartnumeric" and the numbers part of "multipartnumeric+suffix"
   are interpreted as a sequence of numbers and are sorted in
   lexicographical order by these numbers (i.e., not by the digits in
   the numbers) and then the textual suffix (for
   "multipartnumeric+suffix").  "alphanumeric" strings are sorted
   lexicographically as character strings.  "decimal" version numbers
   are interpreted as single floating-point numbers (e.g., 1.25 is less
   than 1.3).

   The values above are registered in the IANA "Software ID Version
   Scheme Values" registry, defined in Section 6.2.4.  Additional
   entries will likely be registered over time in this registry.

   A CoSWID producer that is aware of the version scheme that has been
   used to select the version value SHOULD include the optional version-
   scheme item to avoid semantic ambiguity.  If the CoSWID producer does
   not have this information, it SHOULD omit the version-scheme item.
   The following heuristics can be used by a CoSWID consumer, based on
   the version schemes' partially overlapping value spaces:

   *  "decimal" and "multipartnumeric" partially overlap in their value
      space when a value matches a decimal number.  When a corresponding
      software-version item's value falls within this overlapping value
      space, it is expected that the "decimal" version scheme is used.

   *  "multipartnumeric" and "semver" partially overlap in their value
      space when a "multipartnumeric" value matches the semantic
      versioning syntax.  When a corresponding software-version item's
      value falls within this overlapping value space, it is expected
      that the "semver" version scheme is used.

   *  "alphanumeric" and other version schemes might overlap in their
      value space.  When a corresponding software-version item's value
      falls within this overlapping value space, it is expected that the
      other version scheme is used and "alphanumeric" is not used.

   Note that these heuristics are imperfect and can guess wrong, which
   is the reason the version-scheme item SHOULD be included by the
   producer.

4.2.  Entity Role Values

   The following table indicates the index value to use for the entity-
   entry group's role item (see Section 2.6).  These values match the
   entity roles defined in the ISO/IEC 19770-2:2015 specification
   [SWID].  The "Index" value indicates the value to use as the role
   item's value.  Items in the "Role Name" column provide human-readable
   text for the value.  The "Definition" column describes the semantic
   meaning of each entry.

   +=======+=================+========================================+
   | Index | Role Name       | Definition                             |
   +=======+=================+========================================+
   | 1     | tagCreator      | The person or organization that        |
   |       |                 | created the containing SWID or CoSWID  |
   |       |                 | tag.                                   |
   +-------+-----------------+----------------------------------------+
   | 2     | softwareCreator | The person or organization entity that |
   |       |                 | created the software component.        |
   +-------+-----------------+----------------------------------------+
   | 3     | aggregator      | From [SWID], "An organization or       |
   |       |                 | system that encapsulates software from |
   |       |                 | their own and/or other organizations   |
   |       |                 | into a different distribution process  |
   |       |                 | (as in the case of virtualization), or |
   |       |                 | as a completed system to accomplish a  |
   |       |                 | specific task (as in the case of a     |
   |       |                 | value added reseller)."                |
   +-------+-----------------+----------------------------------------+
   | 4     | distributor     | From [SWID], "An entity that furthers  |
   |       |                 | the marketing, selling and/or          |
   |       |                 | distribution of software from the      |
   |       |                 | original place of manufacture to the   |
   |       |                 | ultimate user without modifying the    |
   |       |                 | software, its packaging or its         |
   |       |                 | labelling."                            |
   +-------+-----------------+----------------------------------------+
   | 5     | licensor        | From [SAM], as a "software licensor",  |
   |       |                 | a "person or organization who owns or  |
   |       |                 | holds the rights to issue a software   |
   |       |                 | license for a specific software        |
   |       |                 | [component]."                          |
   +-------+-----------------+----------------------------------------+
   | 6     | maintainer      | The person or organization that is     |
   |       |                 | responsible for coordinating and       |
   |       |                 | making updates to the source code for  |
   |       |                 | the software component.  This SHOULD   |
   |       |                 | be used when the "maintainer" is a     |
   |       |                 | different person or organization than  |
   |       |                 | the original "softwareCreator".        |
   +-------+-----------------+----------------------------------------+

                       Table 4: Entity Role Values

   The values above are registered in the IANA "Software ID Entity Role
   Values" registry, defined in Section 6.2.5.  Additional values will
   likely be registered over time.

4.3.  Link Ownership Values

   The following table indicates the index value to use for the link-
   entry group's ownership item (see Section 2.7).  These values match
   the link ownership values defined in the ISO/IEC 19770-2:2015
   specification [SWID].  The "Index" value indicates the value to use
   as the link-entry group ownership item's value.  Items in the
   "Ownership Type" column provide human-readable text for the value.
   The "Definition" column describes the semantic meaning of each entry.

   +=======+===========+===============================================+
   | Index | Ownership | Definition                                    |
   |       | Type      |                                               |
   +=======+===========+===============================================+
   | 1     | abandon   | If the software component referenced          |
   |       |           | by the CoSWID tag is uninstalled,             |
   |       |           | then the referenced software SHOULD           |
   |       |           | NOT be uninstalled.                           |
   +-------+-----------+-----------------------------------------------+
   | 2     | private   | If the software component referenced          |
   |       |           | by the CoSWID tag is uninstalled,             |
   |       |           | then the referenced software SHOULD           |
   |       |           | be uninstalled as well.                       |
   +-------+-----------+-----------------------------------------------+
   | 3     | shared    | If the software component referenced          |
   |       |           | by the CoSWID tag is uninstalled,             |
   |       |           | then the referenced software SHOULD           |
   |       |           | be uninstalled if no other                    |
   |       |           | components are sharing the software.          |
   +-------+-----------+-----------------------------------------------+

                       Table 5: Link Ownership Values

   The values above are registered in the IANA "Software ID Link
   Ownership Values" registry, defined in Section 6.2.6.  Additional
   values will likely be registered over time.

4.4.  Link Rel Values

   The following table indicates the index value to use for the link-
   entry group's rel item (see Section 2.7).  These values match the
   link rel values defined in the ISO/IEC 19770-2:2015 specification
   [SWID].  The "Index" value indicates the value to use as the link-
   entry group ownership item's value.  Items in the "Relationship Type"
   column provide human-readable text for the value.  The "Definition"
   column describes the semantic meaning of each entry.

   +=======+===================+======================================+
   | Index | Relationship Type | Definition                           |
   +=======+===================+======================================+
   | 1     | ancestor          | The link references a software tag   |
   |       |                   | for a previous release of this       |
   |       |                   | software.  This can be useful to     |
   |       |                   | define an upgrade path.              |
   +-------+-------------------+--------------------------------------+
   | 2     | component         | The link references a software tag   |
   |       |                   | for a separate component of this     |
   |       |                   | software.                            |
   +-------+-------------------+--------------------------------------+
   | 3     | feature           | The link references a configurable   |
   |       |                   | feature of this software that can be |
   |       |                   | enabled or disabled without changing |
   |       |                   | the installed files.                 |
   +-------+-------------------+--------------------------------------+
   | 4     | installationmedia | The link references the installation |
   |       |                   | package that can be used to install  |
   |       |                   | this software.                       |
   +-------+-------------------+--------------------------------------+
   | 5     | packageinstaller  | The link references the installation |
   |       |                   | software needed to install this      |
   |       |                   | software.                            |
   +-------+-------------------+--------------------------------------+
   | 6     | parent            | The link references a software tag   |
   |       |                   | that is the parent of the            |
   |       |                   | referencing tag.  This relationship  |
   |       |                   | can be used when multiple software   |
   |       |                   | components are part of a software    |
   |       |                   | bundle, where the "parent" is the    |
   |       |                   | software tag for the bundle and each |
   |       |                   | child is a "component".  In such a   |
   |       |                   | case, each child component can       |
   |       |                   | provide a "parent" link relationship |
   |       |                   | to the bundle's software tag, and    |
   |       |                   | the bundle can provide a "component" |
   |       |                   | link relationship to each child      |
   |       |                   | software component.                  |
   +-------+-------------------+--------------------------------------+
   | 7     | patches           | The link references a software tag   |
   |       |                   | that the referencing software        |
   |       |                   | patches.  Typically only used for    |
   |       |                   | patch tags (see Section 1.1).        |
   +-------+-------------------+--------------------------------------+
   | 8     | requires          | The link references a prerequisite   |
   |       |                   | for installing this software.  A     |
   |       |                   | patch tag (see Section 1.1) can use  |
   |       |                   | this to represent base software or   |
   |       |                   | another patch that needs to be       |
   |       |                   | installed first.                     |
   +-------+-------------------+--------------------------------------+
   | 9     | see-also          | The link references other software   |
   |       |                   | that may be of interest that relates |
   |       |                   | to this software.                    |
   +-------+-------------------+--------------------------------------+
   | 10    | supersedes        | The link references other software   |
   |       |                   | (e.g., an older software version)    |
   |       |                   | that this software replaces.  A      |
   |       |                   | patch tag (see Section 1.1) can use  |
   |       |                   | this to represent another patch that |
   |       |                   | this patch incorporates or replaces. |
   +-------+-------------------+--------------------------------------+
   | 11    | supplemental      | The link references a software tag   |
   |       |                   | that the referencing tag             |
   |       |                   | supplements.  Used on supplemental   |
   |       |                   | tags (see Section 1.1).              |
   +-------+-------------------+--------------------------------------+

                    Table 6: Link Relationship Values

   The values above are registered in the IANA "Software ID Link
   Relationship Values" registry, defined in Section 6.2.7.  Additional
   values will likely be registered over time.

4.5.  Link Use Values

   The following table indicates the index value to use for the link-
   entry group's use item (see Section 2.7).  These values match the
   link use values defined in the ISO/IEC 19770-2:2015 specification
   [SWID].  The "Index" value indicates the value to use as the link-
   entry group use item's value.  Items in the "Use Type" column provide
   human-readable text for the value.  The "Definition" column describes
   the semantic meaning of each entry.

     +=======+=============+========================================+
     | Index | Use Type    | Definition                             |
     +=======+=============+========================================+
     | 1     | optional    | From [SWID], "Not absolutely required; |
     |       |             | the [Link]'d software is installed     |
     |       |             | only when specified."                  |
     +-------+-------------+----------------------------------------+
     | 2     | required    | From [SWID], "The [Link]'d software is |
     |       |             | absolutely required for an operation   |
     |       |             | software installation."                |
     +-------+-------------+----------------------------------------+
     | 3     | recommended | From [SWID], "Not absolutely required; |
     |       |             | the [Link]'d software is installed     |
     |       |             | unless specified otherwise."           |
     +-------+-------------+----------------------------------------+

                         Table 7: Link Use Values

   The values above are registered in the IANA "Software ID Link Use
   Values" registry, defined in Section 6.2.8.  Additional values will
   likely be registered over time.

5.  "swid" and "swidpath" Expressions

   This specification defines the following scheme names for use in
   CoSWID and to provide interoperability with scheme names used in
   [SWID].  Because both the "swid" and "swidpath" scheme names are to
   be interpreted within a local (rather than a global) context, neither
   of these are technically URI scheme names as defined in [RFC3986].
   For this reason, the "swid" and "swidpath" scheme names are
   registered with IANA as provisional, rather than permanent, scheme
   names.  However, registering these scheme names as provisional
   ensures that the scheme names are reserved and that they are properly
   defined going forward.

   The swid and swidpath expressions conform to all rules for URI
   syntax.  All uses of these expressions encountered within a CoSWID
   are to be interpreted as described in this section.

5.1.  "swid" Expressions

   Expressions specifying the "swid" scheme are used to reference a
   software tag by its tag-id.  A tag-id referenced in this way can be
   used to identify the tag resource in the context of where it is
   referenced from.  For example, when a tag is installed on a given
   device, that tag can reference related tags on the same device using
   expressions with this scheme.

   For expressions that use the "swid" scheme, the scheme-specific part
   MUST consist of a referenced software tag's tag-id.  This tag-id MUST
   be URI encoded according to Section 2.1 of [RFC3986].

   The following expression is a valid example:

   swid:2df9de35-0aff-4a86-ace6-f7dddd1ade4c

5.2.  "swidpath" Expressions

   Expressions specifying the "swidpath" scheme are used to filter tags
   out of a base collection, so that matching tags are included in the
   identified tag collection.  The XPath expression
   [W3C.REC-xpath20-20101214] references the data that must be found in
   a given software tag out of the base collection for that tag to be
   considered a matching tag.  Tags to be evaluated (the base
   collection) include all tags in the context of where the "swidpath"
   expression is referenced from.  For example, when a tag is installed
   on a given device, that tag can reference related tags on the same
   device using an expression with this scheme.

   For URIs that use the "swidpath" scheme, the following requirements
   apply:

   *  The scheme-specific part MUST be an XPath expression as defined by
      [W3C.REC-xpath20-20101214].  The included XPath expression will be
      URI encoded according to Section 2.1 of [RFC3986].

   *  This XPath is evaluated over SWID tags, or CoSWID tags transformed
      into SWID tags, found on a system.  A given tag MUST be considered
      a match if the XPath evaluation result value has an effective
      boolean value of "true" according to [W3C.REC-xpath20-20101214],
      Section 2.4.3.

6.  IANA Considerations

   This document has a number of IANA considerations, as described in
   the following subsections.  In summary, six new registries are
   established by this document, with initial entries provided for each
   registry.  New values for five other registries are also defined.

6.1.  CoSWID Items Registry

   This document defines a new registry titled "CoSWID Items".  This
   registry uses integer values as index values in CBOR maps.  Future
   registrations for this registry are to be made based on [BCP26] as
   follows:

        +==================+=====================================+
        | Range            | Registration Procedures             |
        +==================+=====================================+
        | 0-32767          | Standards Action with Expert Review |
        +------------------+-------------------------------------+
        | 32768-4294967295 | Specification Required              |
        +------------------+-------------------------------------+

              Table 8: CoSWID Items Registration Procedures

   All negative values are reserved for private use.

   Initial registrations for the "CoSWID Items" registry are provided
   below.  Assignments consist of an integer index value, the item name,
   and a reference to the defining specification.

         +===============+===========================+===========+
         | Index         | Item Name                 | Reference |
         +===============+===========================+===========+
         | 0             | tag-id                    | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 1             | software-name             | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 2             | entity                    | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 3             | evidence                  | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 4             | link                      | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 5             | software-meta             | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 6             | payload                   | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 7             | hash                      | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 8             | corpus                    | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 9             | patch                     | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 10            | media                     | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 11            | supplemental              | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 12            | tag-version               | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 13            | software-version          | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 14            | version-scheme            | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 15            | lang                      | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 16            | directory                 | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 17            | file                      | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 18            | process                   | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 19            | resource                  | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 20            | size                      | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 21            | file-version              | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 22            | key                       | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 23            | location                  | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 24            | fs-name                   | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 25            | root                      | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 26            | path-elements             | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 27            | process-name              | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 28            | pid                       | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 29            | type                      | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 30            | Unassigned                |           |
         +---------------+---------------------------+-----------+
         | 31            | entity-name               | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 32            | reg-id                    | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 33            | role                      | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 34            | thumbprint                | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 35            | date                      | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 36            | device-id                 | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 37            | artifact                  | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 38            | href                      | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 39            | ownership                 | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 40            | rel                       | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 41            | media-type                | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 42            | use                       | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 43            | activation-status         | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 44            | channel-type              | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 45            | colloquial-version        | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 46            | description               | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 47            | edition                   | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 48            | entitlement-data-required | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 49            | entitlement-key           | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 50            | generator                 | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 51            | persistent-id             | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 52            | product                   | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 53            | product-family            | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 54            | revision                  | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 55            | summary                   | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 56            | unspsc-code               | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 57            | unspsc-version            | RFC 9393  |
         +---------------+---------------------------+-----------+
         | 58-4294967295 | Unassigned                |           |
         +---------------+---------------------------+-----------+

                Table 9: CoSWID Items Initial Registrations

6.2.  Registries for Software ID Values

   The following IANA registries provide a mechanism for new values to
   be added over time to common enumerations used by SWID and CoSWID.
   While neither the CoSWID specification nor the SWID specification is
   subordinate to the other and will evolve as their respective
   standards group chooses, there is value in supporting alignment
   between the two standards.  Shared use of common code points, as
   spelled out in these registries, will facilitate this alignment --
   hence the intent for shared use of these registries and the decision
   to use "swidsoftware-id" (rather than "swid" or "coswid") in registry
   names.

6.2.1.  Registration Procedures

   The following registries allow for the registration of index values
   and names.  New registrations will be permitted through either a
   Standards Action with Expert Review policy or a Specification
   Required policy [BCP26].

   The following registries also reserve the integer-based index values
   in the range of -1 to -256 for private use as defined by Section 4.1
   of [BCP26].  This allows values -1 to -24 to be expressed as a single
   uint8_t in CBOR and values -25 to -256 to be expressed using an
   additional uint8_t in CBOR.

6.2.2.  Private Use of Index and Name Values

   The integer-based index values in the private use range (-1 to -256)
   are intended for testing purposes and closed environments; values in
   other ranges SHOULD NOT be assigned for testing.

   For names that correspond to private use index values, an
   Internationalized Domain Name prefix MUST be used to prevent name
   conflicts using the form

   domainprefix/name

   where both "domainprefix" and "name" MUST each be either a Non-
   Reserved LDH (NR-LDH) label or a U-label as defined by [RFC5890], and
   "name" also MUST be a unique name within the namespace defined by the
   "domainprefix".  ("LDH" is an abbreviation for "letters, digits,
   hyphen".)  Using a prefix in this way allows for a name to be used in
   the private use range.  This is consistent with the guidance in
   [BCP178].

6.2.3.  Expert Review Criteria

   Designated experts MUST ensure that new registration requests meet
   the following additional criteria:

   *  The requesting specification MUST provide a clear semantic
      definition for the new entry.  This definition MUST clearly
      differentiate the requested entry from other previously registered
      entries.

   *  The requesting specification MUST describe the intended use of the
      entry, including any co-constraints that exist between (1) the use
      of the entry's index value or name and (2) other values defined
      within the SWID/CoSWID model.

   *  Index values and names outside the private use space MUST NOT be
      used without registration.  This is considered "squatting" and
      MUST be avoided.  Designated experts MUST ensure that reviewed
      specifications register all appropriate index values and names.

   *  Standards Track documents MAY include entries registered in the
      range reserved for entries under the Specification Required
      policy.  This can occur when a Standards Track document provides
      further guidance on the use of index values and names that are in
      common use but were not registered with IANA.  This situation
      SHOULD be avoided.

   *  All registered names MUST be valid according to the XML Schema
      NMTOKEN data type (see [W3C.REC-xmlschema-2-20041028],
      Section 3.3.4).  This ensures that registered names are compatible
      with the SWID format [SWID] where they are used.

   *  Registration of vanity names SHOULD be discouraged.  The
      requesting specification MUST provide a description of how a
      requested name will allow for use by multiple stakeholders.

6.2.4.  Software ID Version Scheme Values Registry

   This document establishes a new registry titled "Software ID Version
   Scheme Values".  This registry provides index values for use as
   version-scheme item values in this document and Version Scheme Names
   for use in [SWID].

   This registry uses the registration procedures defined in
   Section 6.2.1, with the following associated ranges:

           +=============+=====================================+
           | Range       | Registration Procedures             |
           +=============+=====================================+
           | 0-16383     | Standards Action with Expert Review |
           +-------------+-------------------------------------+
           | 16384-65535 | Specification Required              |
           +-------------+-------------------------------------+

             Table 10: Software ID Version Scheme Registration
                                 Procedures

   Assignments MUST consist of an integer index value, the Version
   Scheme Name, and a reference to the defining specification.

   Initial registrations for the "Software ID Version Scheme Values"
   registry are provided below and are derived from the textual Version
   Scheme Names defined in [SWID].

     +=============+=========================+=======================+
     | Index       | Version Scheme Name     | Reference             |
     +=============+=========================+=======================+
     | 0           | Reserved                |                       |
     +-------------+-------------------------+-----------------------+
     | 1           | multipartnumeric        | RFC 9393, Section 4.1 |
     +-------------+-------------------------+-----------------------+
     | 2           | multipartnumeric+suffix | RFC 9393, Section 4.1 |
     +-------------+-------------------------+-----------------------+
     | 3           | alphanumeric            | RFC 9393, Section 4.1 |
     +-------------+-------------------------+-----------------------+
     | 4           | decimal                 | RFC 9393, Section 4.1 |
     +-------------+-------------------------+-----------------------+
     | 5-16383     | Unassigned              |                       |
     +-------------+-------------------------+-----------------------+
     | 16384       | semver                  | RFC 9393, Section 4.1 |
     +-------------+-------------------------+-----------------------+
     | 16385-65535 | Unassigned              |                       |
     +-------------+-------------------------+-----------------------+

         Table 11: Software ID Version Scheme Initial Registrations

   Registrations MUST conform to the expert review criteria defined in
   Section 6.2.3.

   Designated experts MUST also ensure that newly requested entries
   define a value space for the corresponding software-version item that
   is unique from other previously registered entries.

      |  Note: The initial registrations violate this requirement but
      |  are included for backwards compatibility with [SWID].  See also
      |  Section 4.1.

6.2.5.  Software ID Entity Role Values Registry

   This document establishes a new registry titled "Software ID Entity
   Role Values".  This registry provides index values for use as entity-
   entry role item values in this document and entity role names for use
   in [SWID].

   This registry uses the registration procedures defined in
   Section 6.2.1, with the following associated ranges:

             +=========+=====================================+
             | Range   | Registration Procedures             |
             +=========+=====================================+
             | 0-127   | Standards Action with Expert Review |
             +---------+-------------------------------------+
             | 128-255 | Specification Required              |
             +---------+-------------------------------------+

                     Table 12: Software ID Entity Role
                          Registration Procedures

   Assignments consist of an integer index value, a role name, and a
   reference to the defining specification.

   Initial registrations for the "Software ID Entity Role Values"
   registry are provided below and are derived from the textual entity
   role names defined in [SWID].

            +=======+=================+=======================+
            | Index | Role Name       | Reference             |
            +=======+=================+=======================+
            | 0     | Reserved        |                       |
            +-------+-----------------+-----------------------+
            | 1     | tagCreator      | RFC 9393, Section 4.2 |
            +-------+-----------------+-----------------------+
            | 2     | softwareCreator | RFC 9393, Section 4.2 |
            +-------+-----------------+-----------------------+
            | 3     | aggregator      | RFC 9393, Section 4.2 |
            +-------+-----------------+-----------------------+
            | 4     | distributor     | RFC 9393, Section 4.2 |
            +-------+-----------------+-----------------------+
            | 5     | licensor        | RFC 9393, Section 4.2 |
            +-------+-----------------+-----------------------+
            | 6     | maintainer      | RFC 9393, Section 4.2 |
            +-------+-----------------+-----------------------+
            | 7-255 | Unassigned      |                       |
            +-------+-----------------+-----------------------+

                 Table 13: Software ID Entity Role Initial
                               Registrations

   Registrations MUST conform to the expert review criteria defined in
   Section 6.2.3.

6.2.6.  Software ID Link Ownership Values Registry

   This document establishes a new registry titled "Software ID Link
   Ownership Values".  This registry provides index values for use as
   link-entry ownership item values in this document and link ownership
   names for use in [SWID].

   This registry uses the registration procedures defined in
   Section 6.2.1, with the following associated ranges:

             +=========+=====================================+
             | Range   | Registration Procedures             |
             +=========+=====================================+
             | 0-127   | Standards Action with Expert Review |
             +---------+-------------------------------------+
             | 128-255 | Specification Required              |
             +---------+-------------------------------------+

                    Table 14: Software ID Link Ownership
                          Registration Procedures

   Assignments consist of an integer index value, an ownership type
   name, and a reference to the defining specification.

   Initial registrations for the "Software ID Link Ownership Values"
   registry are provided below and are derived from the textual entity
   role names defined in [SWID].

          +=======+=====================+=======================+
          | Index | Ownership Type Name | Reference             |
          +=======+=====================+=======================+
          | 0     | Reserved            |                       |
          +-------+---------------------+-----------------------+
          | 1     | abandon             | RFC 9393, Section 4.3 |
          +-------+---------------------+-----------------------+
          | 2     | private             | RFC 9393, Section 4.3 |
          +-------+---------------------+-----------------------+
          | 3     | shared              | RFC 9393, Section 4.3 |
          +-------+---------------------+-----------------------+
          | 4-255 | Unassigned          |                       |
          +-------+---------------------+-----------------------+

                Table 15: Software ID Link Ownership Initial
                               Registrations

   Registrations MUST conform to the expert review criteria defined in
   Section 6.2.3.

6.2.7.  Software ID Link Relationship Values Registry

   This document establishes a new registry titled "Software ID Link
   Relationship Values".  This registry provides index values for use as
   link-entry rel item values in this document and link ownership names
   for use in [SWID].

   This registry uses the registration procedures defined in
   Section 6.2.1, with the following associated ranges:

           +=============+=====================================+
           | Range       | Registration Procedures             |
           +=============+=====================================+
           | 0-32767     | Standards Action with Expert Review |
           +-------------+-------------------------------------+
           | 32768-65535 | Specification Required              |
           +-------------+-------------------------------------+

                  Table 16: Software ID Link Relationship
                          Registration Procedures

   Assignments consist of an integer index value, the relationship type
   name, and a reference to the defining specification.

   Initial registrations for the "Software ID Link Relationship Values"
   registry are provided below and are derived from the link
   relationship values defined in [SWID].

       +==========+========================+=======================+
       | Index    | Relationship Type Name | Reference             |
       +==========+========================+=======================+
       | 0        | Reserved               |                       |
       +----------+------------------------+-----------------------+
       | 1        | ancestor               | RFC 9393, Section 4.4 |
       +----------+------------------------+-----------------------+
       | 2        | component              | RFC 9393, Section 4.4 |
       +----------+------------------------+-----------------------+
       | 3        | feature                | RFC 9393, Section 4.4 |
       +----------+------------------------+-----------------------+
       | 4        | installationmedia      | RFC 9393, Section 4.4 |
       +----------+------------------------+-----------------------+
       | 5        | packageinstaller       | RFC 9393, Section 4.4 |
       +----------+------------------------+-----------------------+
       | 6        | parent                 | RFC 9393, Section 4.4 |
       +----------+------------------------+-----------------------+
       | 7        | patches                | RFC 9393, Section 4.4 |
       +----------+------------------------+-----------------------+
       | 8        | requires               | RFC 9393, Section 4.4 |
       +----------+------------------------+-----------------------+
       | 9        | see-also               | RFC 9393, Section 4.4 |
       +----------+------------------------+-----------------------+
       | 10       | supersedes             | RFC 9393, Section 4.4 |
       +----------+------------------------+-----------------------+
       | 11       | supplemental           | RFC 9393, Section 4.4 |
       +----------+------------------------+-----------------------+
       | 12-65535 | Unassigned             |                       |
       +----------+------------------------+-----------------------+

       Table 17: Software ID Link Relationship Initial Registrations

   Registrations MUST conform to the expert review criteria defined in
   Section 6.2.3.

   Designated experts MUST also ensure that a newly requested entry
   documents the URI schemes allowed to be used in an href associated
   with the link relationship and the expected resolution behavior of
   these URI schemes.  This will help to ensure that applications
   processing software tags are able to interoperate when resolving
   resources referenced by a link of a given type.

6.2.8.  Software ID Link Use Values Registry

   This document establishes a new registry titled "Software ID Link Use
   Values".  This registry provides index values for use as link-entry
   use item values in this document and link use names for use in
   [SWID].

   This registry uses the registration procedures defined in
   Section 6.2.1, with the following associated ranges:

             +=========+=====================================+
             | Range   | Registration Procedures             |
             +=========+=====================================+
             | 0-127   | Standards Action with Expert Review |
             +---------+-------------------------------------+
             | 128-255 | Specification Required              |
             +---------+-------------------------------------+

                Table 18: Software ID Link Use Registration
                                 Procedures

   Assignments consist of an integer index value, the link use type
   name, and a reference to the defining specification.

   Initial registrations for the "Software ID Link Use Values" registry
   are provided below and are derived from the link relationship values
   defined in [SWID].

          +=======+====================+=======================+
          | Index | Link Use Type Name | Reference             |
          +=======+====================+=======================+
          | 0     | Reserved           |                       |
          +-------+--------------------+-----------------------+
          | 1     | optional           | RFC 9393, Section 4.5 |
          +-------+--------------------+-----------------------+
          | 2     | required           | RFC 9393, Section 4.5 |
          +-------+--------------------+-----------------------+
          | 3     | recommended        | RFC 9393, Section 4.5 |
          +-------+--------------------+-----------------------+
          | 4-255 | Unassigned         |                       |
          +-------+--------------------+-----------------------+

           Table 19: Software ID Link Use Initial Registrations

   Registrations MUST conform to the expert review criteria defined in
   Section 6.2.3.

6.3.  swid+cbor Media Type Registration

   IANA has added the following to the "Media Types" registry
   [IANA.media-types].

   Type name:  application

   Subtype name:  swid+cbor

   Required parameters:  none

   Optional parameters:  none

   Encoding considerations:  Binary (encoded as CBOR [RFC8949]).  See
      RFC 9393 for details.

   Security considerations:  See Section 9 of RFC 9393.

   Interoperability considerations:  Applications MAY ignore any key
      value pairs that they do not understand.  This allows backwards-
      compatible extensions to this specification.

   Published specification:  RFC 9393

   Applications that use this media type:  The type is used by software
      asset management systems and vulnerability assessment systems and
      is used in applications that use remote integrity verification.

   Fragment Identifier Considerations:  The syntax and semantics of
      fragment identifiers specified for "application/swid+cbor" are as
      specified for "application/cbor".  (At publication of RFC 9393,
      there is no fragment identification syntax defined for
      "application/cbor".)

   Additional information:
      Magic number(s):  If tagged, the first five bytes in hex: da 53 57
         49 44 (see Section 8 of RFC 9393).
      File extension(s):  coswid
      Macintosh file type code(s):  none
      Macintosh Universal Type Identifier code:  org.ietf.coswid
         conforms to public.data.

   Person & email address to contact for further information:
      IESG <iesg@ietf.org>

   Intended usage:  COMMON

   Restrictions on usage:  none

   Author:  Henk Birkholz <henk.birkholz@sit.fraunhofer.de>

   Change controller:  IESG

6.4.  CoAP Content-Format Registration

   IANA has assigned a CoAP Content-Format ID for the CoSWID media type
   in the "CoAP Content-Formats" subregistry, from the "IETF Review or
   IESG Approval" space (256..999), within the "CoRE Parameters"
   registry [RFC7252] [IANA.core-parameters]:

       +=======================+================+=====+===========+
       | Content Type          | Content Coding | ID  | Reference |
       +=======================+================+=====+===========+
       | application/swid+cbor | -              | 258 | RFC 9393  |
       +-----------------------+----------------+-----+-----------+

                    Table 20: CoAP Content-Format IDs

6.5.  CBOR Tag Registration

   IANA has allocated a tag in the "CBOR Tags" registry
   [IANA.cbor-tags]:

       +============+===========+=====================+===========+
       | Tag        | Data Item | Semantics           | Reference |
       +============+===========+=====================+===========+
       | 1398229316 | map       | Concise Software    | RFC 9393  |
       |            |           | Identifier (CoSWID) |           |
       +------------+-----------+---------------------+-----------+

                        Table 21: CoSWID CBOR Tag

6.6.  URI Scheme Registrations

   The ISO 19770-2:2015 SWID specification [SWID] describes the use of
   the "swid" and "swidpath" URI schemes, which are currently in use in
   implementations.  This document continues this use for CoSWID.  The
   following subsections provide registrations for these schemes to
   ensure that a registration for these schemes exists that is suitable
   for use in the SWID and CoSWID specifications.

   URI schemes are registered within the "Uniform Resource Identifier
   (URI) Schemes" registry maintained at [IANA.uri-schemes].

6.6.1.  URI Scheme "swid"

   IANA has registered the URI scheme "swid".  This registration
   complies with [RFC7595].

   Scheme name:  swid

   Status:  Provisional

   Applications/protocols that use this scheme name:  Applications that
      require Software IDs (SWIDs) or Concise Software IDs (CoSWIDs);
      see Section 5.1 of RFC 9393.

   Contact:  IETF Chair <chair@ietf.org>

   Change controller:  IESG <iesg@ietf.org>

   Reference:  Section 5.1 of RFC 9393

      |  Note: This scheme has been documented by an IETF working group
      |  and is mentioned in an IETF Standard specification.  However,
      |  as it describes a locally scoped, limited-purpose form of
      |  identification, it does not fully meet the requirements for
      |  permanent registration.
      |  
      |  As long as this specification (or any successors that describe
      |  this scheme) is a current IETF specification, this scheme
      |  should be considered to be "in use" and not considered for
      |  removal from the registry.

6.6.2.  URI Scheme "swidpath"

   IANA has registered the URI scheme "swidpath".  This registration
   complies with [RFC7595].

   Scheme name:  swidpath

   Status:  Provisional

   Applications/protocols that use this scheme name:  Applications that
      require Software IDs (SWIDs) or Concise Software IDs (CoSWIDs);
      see Section 5.2 of RFC 9393.

   Contact:  IETF Chair <chair@ietf.org>

   Change controller:  IESG <iesg@ietf.org>

   Reference:  Section 5.2 of RFC 9393

      |  Note: This scheme has been documented by an IETF working group
      |  and is mentioned in an IETF Standard specification.  However,
      |  as it describes a locally scoped, limited-purpose form of
      |  identification, it does not fully meet the requirements for
      |  permanent registration.
      |  
      |  As long as this specification (or any successors that describe
      |  this scheme) is a current IETF specification, this scheme
      |  should be considered to be "in use" and not considered for
      |  removal from the registry.

6.7.  CoSWID Model for Use in SWIMA Registration

   "Software Inventory Message and Attributes (SWIMA) for PA-TNC"
   [RFC8412] defines a standardized method for collecting an endpoint
   device's software inventory.  A CoSWID can provide evidence of
   software installation that can then be used and exchanged with SWIMA.
   This registration adds a new entry to the IANA "Software Data Model
   Types" registry defined by [RFC8412] and [IANA.pa-tnc-parameters] to
   support CoSWID use in SWIMA as follows:

   Pen:  0

   Integer:  2

   Name:  Concise Software Identifier (CoSWID)

   Reference:  RFC 9393

   Deriving Software Identifiers:  A Software Identifier generated from
      a CoSWID tag is expressed as a concatenation of the form used in
      [RFC5234] as follows --

      TAG_CREATOR_REGID "_" "_" UNIQUE_ID

      where TAG_CREATOR_REGID is the reg-id item value of the tag's
      entity item having the role value of 1 (corresponding to "tag-
      creator"), and the UNIQUE_ID is the same tag's tag-id item.  If
      the tag-id item's value is expressed as a 16-byte binary string,
      the UNIQUE_ID MUST be represented using the UUID string
      representation defined in [RFC4122], including the "urn:uuid:"
      prefix.

      The TAG_CREATOR_REGID and the UNIQUE_ID are connected with a
      double underscore (_), without any other connecting character or
      whitespace.

7.  Signed CoSWID Tags

   SWID tags, as defined in the ISO-19770-2:2015 XML Schema, can include
   cryptographic signatures to protect the integrity of the SWID tag.
   In general, tags are signed by the tag creator (typically, although
   not exclusively, the vendor of the software component that the SWID
   tag identifies).  Cryptographic signatures can make any modification
   of the tag detectable, which is especially important if the integrity
   of the tag is important, such as when the tag is providing RIMs for
   files.  The ISO-19770-2:2015 XML Schema uses XML Digital Signatures
   (XMLDSIG) to support cryptographic signatures.

   Signing CoSWID tags follows the procedures defined in CBOR Object
   Signing and Encryption (COSE) [RFC9052].  A CoSWID tag MUST be
   wrapped in a COSE Signature structure, either COSE_Sign1 or
   COSE_Sign.  In the first case, a Single Signer Data Object
   (COSE_Sign1) contains a single signature and MUST be signed by the
   tag creator.  The following CDDL specification defines a restrictive
   subset of COSE header parameters that MUST be used in the protected
   header in this case.

   <CODE BEGINS> file "sign1.cddl"
   COSE_Sign1-coswid<payload> = [
       protected: bstr .cbor protected-signed-coswid-header,
       unprotected: unprotected-signed-coswid-header,
       payload: bstr .cbor payload,
       signature: bstr,
   ]

   cose-label = int / tstr
   cose-values = any

   protected-signed-coswid-header = {
       1 => int,                      ; algorithm identifier
       3 => "application/swid+cbor",
       * cose-label => cose-values,
   }

   unprotected-signed-coswid-header = {
       * cose-label => cose-values,
   }
   <CODE ENDS>

   The COSE_Sign structure allows for more than one signature, one of
   which MUST be issued by the tag creator, to be applied to a CoSWID
   tag and MAY be used.  The corresponding usage scenarios are domain
   specific and require well-specified application guidance.

   <CODE BEGINS> file "sign.cddl"
   COSE_Sign-coswid<payload> = [
       protected: bstr .cbor protected-signed-coswid-header1,
       unprotected: unprotected-signed-coswid-header,
       payload: bstr .cbor payload,
       signature: [ * COSE_Signature ],
   ]

   protected-signed-coswid-header1 = {
       3 => "application/swid+cbor",
       * cose-label => cose-values,
   }

   protected-signature-coswid-header = {
       1 => int,                      ; algorithm identifier
       * cose-label => cose-values,
   }

   unprotected-signed-coswid-header = {
       * cose-label => cose-values,
   }

   COSE_Signature =  [
       protected: bstr .cbor protected-signature-coswid-header,
       unprotected: unprotected-signed-coswid-header,
       signature: bstr
   ]
   <CODE ENDS>

   Additionally, the COSE header countersignature MAY be used as an
   attribute in the unprotected header map of the COSE envelope of a
   CoSWID [RFC9338].  The application of countersigning enables second
   parties to provide a signature on a signature allowing for proof that
   a signature existed at a given time (i.e., a timestamp).

   A CoSWID MUST be signed, using the above mechanism, to protect the
   integrity of the CoSWID tag.  See Section 9 ("Security
   Considerations") for more information on why a signed CoSWID is
   valuable in most cases.

8.  CBOR-Tagged CoSWID Tags

   This specification allows for tagged and untagged CBOR data items
   that are CoSWID tags.  Consequently, the CBOR tag defined by this
   document (Table 21) for CoSWID tags SHOULD be used in conjunction
   with CBOR data items that are CoSWID tags.  Other CBOR tags MUST NOT
   be used with a CBOR data item that is a CoSWID tag.  If tagged, both
   signed and unsigned CoSWID tags MUST use the CoSWID CBOR tag.  If a
   signed CoSWID is tagged, a CoSWID CBOR tag MUST be appended before
   the COSE envelope, whether it is a COSE_Untagged_Message or a
   COSE_Tagged_Message.  If an unsigned CoSWID is tagged, a CoSWID CBOR
   tag MUST be appended before the CBOR data item that is the CoSWID
   tag.

   <CODE BEGINS> file "tags.cddl"
   coswid = unsigned-coswid / signed-coswid
   unsigned-coswid = concise-swid-tag / tagged-coswid<concise-swid-tag>
   signed-coswid1 = signed-coswid-for<unsigned-coswid>
   signed-coswid = signed-coswid1 / tagged-coswid<signed-coswid1>

   tagged-coswid<T> = #6.1398229316(T)

   signed-coswid-for<payload> = #6.18(COSE_Sign1-coswid<payload>)
       / #6.98(COSE_Sign-coswid<payload>)
   <CODE ENDS>

   This specification allows for a CBOR-tagged CoSWID tag to reside in a
   COSE envelope that is also tagged with a CoSWID CBOR tag.  In cases
   where a tag creator is not a signer (e.g., hand-offs between entities
   in a trusted portion of a supply chain), retaining CBOR tags attached
   to unsigned CoSWID tags can be of great use.  Nevertheless, redundant
   use of tags SHOULD be avoided when possible.

9.  Security Considerations

   The following security considerations for the use of CoSWID tags
   focus on:

   *  ensuring the integrity and authenticity of a CoSWID tag

   *  the application of CoSWID tags to address security challenges
      related to unmanaged or unpatched software

   *  reducing the potential for unintended disclosure of a device's
      software load

   A tag is considered "authoritative" if the CoSWID tag was created by
   the software provider.  An authoritative CoSWID tag contains
   information about a software component provided by the supplier of
   the software component, who is expected to be an expert in their own
   software.  Thus, authoritative CoSWID tags can represent
   authoritative information about the software component.  The degree
   to which this information can be trusted depends on the tag's chain
   of custody and the ability to verify a signature provided by the
   supplier if present in the CoSWID tag.  The provisioning and
   validation of CoSWID tags are handled by local policy and are outside
   the scope of this document.

   A signed CoSWID tag (see Section 7) whose signature has been
   validated can be relied upon to be unchanged since the time at which
   it was signed.  By contrast, the data contained in unsigned tags can
   be altered by any user or process with write access to the tag.  To
   support signature validation, there is a need to associate the right
   key with the software provider or party originating the signature in
   a secure way.  This operation is application specific and needs to be
   addressed by the application or a user of the application; a specific
   approach for this topic is out of scope for this document.

   When an authoritative tag is signed, the originator of the signature
   can be verified.  A trustworthy association between the signature and
   the originator of the signature can be established via trust anchors.
   A certification path between a trust anchor and a certificate,
   including a public key enabling the validation of a tag signature,
   can realize the assessment of trustworthiness of an authoritative
   tag.  Verifying that the software provider is the signer is a
   different matter.  This requires verifying that the party that signed
   the tag is the same party given in the software-creator role of the
   tag's entity item.  No mechanism is defined in this document to make
   this association; therefore, this association will need to be handled
   by local policy.  As always, the validity of a signature does not
   imply the veracity of the signed statements: anyone can sign
   assertions such that the software is from a specific software-creator
   or that a specific persistent-id applies; policy needs to be applied
   to evaluate these statements and to determine their suitability for a
   specific use.

   Loss of control of signing credentials used to sign CoSWID tags would
   cast doubt on the authenticity and integrity of any CoSWID tags
   signed using the compromised keys.  In such cases, the legitimate tag
   signer (namely, the software provider for an authoritative CoSWID
   tag) can employ uncompromised signing credentials to create a new
   signature on the original tag.  The tag's version number would not be
   incremented, since the tag itself was not modified.  Consumers of
   CoSWID tags would need to validate the tag using the new credentials
   and would also need to make use of revocation information available
   for the compromised credentials to avoid validating tags signed with
   them.  The process for doing this is beyond the scope of this
   specification.

   The CoSWID format allows the use of hash values without an
   accompanying hash algorithm identifier.  This exposes the tags to
   some risk of cross-algorithm attacks.  We believe that this can
   become a practical problem only if some implementations allow the use
   of insecure hash algorithms.  Since it may not become known
   immediately when an algorithm becomes insecure, this leads to a
   strong recommendation to only include support for hash algorithms
   that are generally considered secure, and not just marginally so.

   CoSWID tags are intended to contain public information about software
   components and, as such, the contents of a CoSWID tag (as opposed to
   the set of tags that apply to the endpoint; see below) do not need to
   be protected against unintended disclosure on an endpoint.
   Conversely, generators of CoSWID tags need to ensure that only public
   information is disclosed.  The entitlement-key item is an example of
   information for which particular care is required; tag authors are
   advised not to record unprotected, private software license keys in
   this field.

   CoSWID tags are intended to be easily discoverable by authorized
   applications and users on an endpoint in order to make it easy to
   determine the tagged software load.  Access to the collection of an
   endpoint's CoSWID tags needs to be limited to authorized applications
   and users using an appropriate access control mechanism.

   Since the tag-id of a CoSWID tag can be used as a global index value,
   failure to ensure the tag-id's uniqueness can cause collisions or
   ambiguity in CoSWID tags that are retrieved or processed using this
   identifier.  CoSWID is designed to not require a registry of
   identifiers.  As a result, CoSWID requires the tag creator to employ
   a method of generating a unique tag identifier.  Specific methods of
   generating a unique identifier are beyond the scope of this
   specification.  A collision in tag-ids may result in false positives/
   negatives in software integrity checks or misidentification of
   installed software, undermining CoSWID use cases such as
   vulnerability identification, software inventory, etc.  If such a
   collision is detected, then the tag consumer may want to contact the
   maintainer of the CoSWID to have them issue a correction addressing
   the collision; however, this also discloses to the maintainer that
   the consumer has the other tag with the given tag-id in their
   database.  More generally speaking, a tag consumer needs to be robust
   against such collisions lest the collision become a viable attack
   vector.

   CoSWID tags are designed to be easily added and removed from an
   endpoint along with the installation or removal of software
   components.  On endpoints where the addition or removal of software
   components is tightly controlled, the addition or removal of CoSWID
   tags can be similarly controlled.  On more open systems, where many
   users can manage the software inventory, CoSWID tags can be easier to
   add or remove.  On such systems, it can be possible to add or remove
   CoSWID tags in a way that does not reflect the actual presence or
   absence of corresponding software components.  Similarly, not all
   software products automatically install CoSWID tags, so products can
   be present on an endpoint without providing a corresponding CoSWID
   tag.  As such, any collection of CoSWID tags cannot automatically be
   assumed to represent either a complete or fully accurate
   representation of the software inventory of the endpoint.  However,
   especially on endpoint devices that more strictly control the ability
   to add or remove applications, CoSWID tags are an easy way to provide
   a preliminary understanding of that endpoint's software inventory.

   As CoSWID tags do not expire, inhibiting new CoSWID tags from
   reaching an intended consumer would render that consumer stuck with
   outdated information, potentially leaving associated vulnerabilities
   or weaknesses unmitigated.  Therefore, a CoSWID tag consumer should
   actively check for updated tag-versions via more than one means.

   This specification makes use of relative paths (e.g., filesystem
   paths) in several places.  A signed CoSWID tag cannot make use of
   these to derive information that is considered to be covered under
   the signature.  Typically, relative filesystem paths will be used to
   identify targets for an installation, not sources of tag information.

   Any report of an endpoint's CoSWID tag collection provides
   information about the software inventory of that endpoint.  If such a
   report is exposed to an attacker, this can tell them which software
   products and versions thereof are present on the endpoint.  By
   examining this list, the attacker might learn of the presence of
   applications that are vulnerable to certain types of attacks.  As
   noted earlier, CoSWID tags are designed to be easily discoverable by
   authorized applications and users on an endpoint, but this does not
   present a significant risk, since an attacker would already need to
   have access to the endpoint to view that information.  However, when
   the endpoint transmits its software inventory to another party or
   that inventory is stored on a server for later analysis, this can
   potentially expose this information to attackers who do not yet have
   access to the endpoint.  For this reason, it is important to protect
   the confidentiality of CoSWID tag information that has been collected
   from an endpoint in transit and at rest, not because those tags
   individually contain sensitive information but because the collection
   of CoSWID tags and their association with an endpoint reveals
   information about that endpoint's attack surface.

   Finally, both the ISO-19770-2:2015 XML Schema SWID definition and the
   CoSWID CDDL specification allow for the construction of "infinite"
   tags with link item loops or tags that contain malicious content with
   the intent of creating non-deterministic states during validation or
   processing of those tags.  While software providers are unlikely to
   do this, CoSWID tags can be created by any party and the CoSWID tags
   collected from an endpoint could contain a mixture of tags created by
   vendors and tags not created by vendors.  For this reason, a CoSWID
   tag might contain potentially malicious content.  Input sanitization,
   loop detection, and signature verification are ways that
   implementations can address this concern.

   More generally speaking, the Security Considerations sections of
   [RFC8949], [RFC9052], and [RFC9338] apply.

10.  Privacy Considerations

   As noted in Section 9, collected information about an endpoint's
   software load, such as what might be represented by an endpoint's
   CoSWID tag collection, could be used by attackers to identify
   vulnerable software.  Collections of endpoint software information
   also can have privacy implications for users.  The set of
   applications a user installs can provide clues regarding personal
   matters such as political affiliation, banking and investments,
   gender, sexual orientation, medical concerns, etc.  While the
   collection of CoSWID tags on an endpoint wouldn't increase privacy
   risks (since a party able to view those tags could also view the
   applications themselves), if those CoSWID tags are gathered and
   stored in a repository somewhere, visibility into the repository now
   also provides visibility into a user's application collection.  For
   this reason, not only do repositories of collected CoSWID tags need
   to be protected against collection by malicious parties but even
   authorized parties will need to be vetted and made aware of privacy
   responsibilities associated with having access to this information.
   Likewise, users should be made aware that their software inventories
   are being collected from endpoints.  Furthermore, when collected and
   stored by authorized parties or systems, the inventory data needs to
   be protected as both security and privacy-sensitive information.

11.  References

11.1.  Normative References

   [BCP178]   Saint-Andre, P., Crocker, D., and M. Nottingham,
              "Deprecating the "X-" Prefix and Similar Constructs in
              Application Protocols", BCP 178, RFC 6648, June 2012.

              <https://www.rfc-editor.org/info/bcp178>

   [BCP26]    Cotton, M., Leiba, B., and T. Narten, "Guidelines for
              Writing an IANA Considerations Section in RFCs", BCP 26,
              RFC 8126, June 2017.

              <https://www.rfc-editor.org/info/bcp26>

   [IANA.cbor-tags]
              IANA, "Concise Binary Object Representation (CBOR) Tags",
              <https://www.iana.org/assignments/cbor-tags>.

   [IANA.core-parameters]
              IANA, "Constrained RESTful Environments (CoRE)
              Parameters",
              <https://www.iana.org/assignments/core-parameters>.

   [IANA.media-types]
              IANA, "Media Types",
              <https://www.iana.org/assignments/media-types>.

   [IANA.named-information]
              IANA, "Named Information",
              <https://www.iana.org/assignments/named-information>.

   [IANA.pa-tnc-parameters]
              IANA, "Posture Attribute (PA) Protocol Compatible with
              Trusted Network Connect (TNC) Parameters",
              <https://www.iana.org/assignments/pa-tnc-parameters>.

   [IANA.uri-schemes]
              IANA, "Uniform Resource Identifier (URI) Schemes",
              <https://www.iana.org/assignments/uri-schemes>.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC3629]  Yergeau, F., "UTF-8, a transformation format of ISO
              10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, November
              2003, <https://www.rfc-editor.org/info/rfc3629>.

   [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
              Resource Identifier (URI): Generic Syntax", STD 66,
              RFC 3986, DOI 10.17487/RFC3986, January 2005,
              <https://www.rfc-editor.org/info/rfc3986>.

   [RFC5198]  Klensin, J. and M. Padlipsky, "Unicode Format for Network
              Interchange", RFC 5198, DOI 10.17487/RFC5198, March 2008,
              <https://www.rfc-editor.org/info/rfc5198>.

   [RFC5234]  Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
              Specifications: ABNF", STD 68, RFC 5234,
              DOI 10.17487/RFC5234, January 2008,
              <https://www.rfc-editor.org/info/rfc5234>.

   [RFC5646]  Phillips, A., Ed. and M. Davis, Ed., "Tags for Identifying
              Languages", BCP 47, RFC 5646, DOI 10.17487/RFC5646,
              September 2009, <https://www.rfc-editor.org/info/rfc5646>.

   [RFC5890]  Klensin, J., "Internationalized Domain Names for
              Applications (IDNA): Definitions and Document Framework",
              RFC 5890, DOI 10.17487/RFC5890, August 2010,
              <https://www.rfc-editor.org/info/rfc5890>.

   [RFC7252]  Shelby, Z., Hartke, K., and C. Bormann, "The Constrained
              Application Protocol (CoAP)", RFC 7252,
              DOI 10.17487/RFC7252, June 2014,
              <https://www.rfc-editor.org/info/rfc7252>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

   [RFC8288]  Nottingham, M., "Web Linking", RFC 8288,
              DOI 10.17487/RFC8288, October 2017,
              <https://www.rfc-editor.org/info/rfc8288>.

   [RFC8412]  Schmidt, C., Haynes, D., Coffin, C., Waltermire, D., and
              J. Fitzgerald-McKay, "Software Inventory Message and
              Attributes (SWIMA) for PA-TNC", RFC 8412,
              DOI 10.17487/RFC8412, July 2018,
              <https://www.rfc-editor.org/info/rfc8412>.

   [RFC8610]  Birkholz, H., Vigano, C., and C. Bormann, "Concise Data
              Definition Language (CDDL): A Notational Convention to
              Express Concise Binary Object Representation (CBOR) and
              JSON Data Structures", RFC 8610, DOI 10.17487/RFC8610,
              June 2019, <https://www.rfc-editor.org/info/rfc8610>.

   [RFC8949]  Bormann, C. and P. Hoffman, "Concise Binary Object
              Representation (CBOR)", STD 94, RFC 8949,
              DOI 10.17487/RFC8949, December 2020,
              <https://www.rfc-editor.org/info/rfc8949>.

   [RFC9052]  Schaad, J., "CBOR Object Signing and Encryption (COSE):
              Structures and Process", STD 96, RFC 9052,
              DOI 10.17487/RFC9052, August 2022,
              <https://www.rfc-editor.org/info/rfc9052>.

   [RFC9338]  Schaad, J., "CBOR Object Signing and Encryption (COSE):
              Countersignatures", STD 96, RFC 9338,
              DOI 10.17487/RFC9338, December 2022,
              <https://www.rfc-editor.org/info/rfc9338>.

   [SAM]      "Information technology - IT asset management - Part 5:
              Overview and vocabulary", ISO/IEC 19770-5:2015, August
              2015, <https://www.iso.org/standard/68291.html>.

   [SWID]     "Information technology - IT asset management - Part 2:
              Software identification tag", ISO/IEC 19770-2:2015,
              October 2015, <https://www.iso.org/standard/65666.html>.

   [UNSPSC]   "United Nations Standard Products and Services Code",
              2022, <https://www.unspsc.org/>.

   [W3C.REC-mediaqueries-3-20220405]
              Rivoal, F., Ed., "Media Queries Level 3", W3C
              Recommendation REC-mediaqueries-3-20220405, 5 April 2022,
              <https://www.w3.org/TR/mediaqueries-3/>.

   [W3C.REC-xmlschema-2-20041028]
              Biron, P. V., Ed. and A. Malhotra, Ed., "XML Schema Part
              2: Datatypes Second Edition", W3C Recommendation REC-
              xmlschema-2-20041028, 28 October 2004,
              <https://www.w3.org/TR/2004/REC-xmlschema-2-20041028/>.

   [W3C.REC-xpath20-20101214]
              Berglund, A., Ed., Boag, S., Ed., Chamberlin, D., Ed.,
              Fernández, M. F., Ed., Kay, M., Ed., Robie, J., Ed., and
              J. Siméon, Ed., "XML Path Language (XPath) 2.0 (Second
              Edition)", W3C Recommendation REC-xpath20-20101214, 14
              December 2010,
              <https://www.w3.org/TR/2010/REC-xpath20-20101214/>.

11.2.  Informative References

   [CamelCase]
              "Camel Case (upper camel case)", 18 December 2014,
              <http://wiki.c2.com/?CamelCase>.

   [KebabCase]
              "Kebab Case", 29 August 2014,
              <http://wiki.c2.com/?KebabCase>.

   [RFC3444]  Pras, A. and J. Schoenwaelder, "On the Difference between
              Information Models and Data Models", RFC 3444,
              DOI 10.17487/RFC3444, January 2003,
              <https://www.rfc-editor.org/info/rfc3444>.

   [RFC4122]  Leach, P., Mealling, M., and R. Salz, "A Universally
              Unique IDentifier (UUID) URN Namespace", RFC 4122,
              DOI 10.17487/RFC4122, July 2005,
              <https://www.rfc-editor.org/info/rfc4122>.

   [RFC7595]  Thaler, D., Ed., Hansen, T., and T. Hardie, "Guidelines
              and Registration Procedures for URI Schemes", BCP 35,
              RFC 7595, DOI 10.17487/RFC7595, June 2015,
              <https://www.rfc-editor.org/info/rfc7595>.

   [RFC8322]  Field, J., Banghart, S., and D. Waltermire, "Resource-
              Oriented Lightweight Information Exchange (ROLIE)",
              RFC 8322, DOI 10.17487/RFC8322, February 2018,
              <https://www.rfc-editor.org/info/rfc8322>.

   [RFC8520]  Lear, E., Droms, R., and D. Romascanu, "Manufacturer Usage
              Description Specification", RFC 8520,
              DOI 10.17487/RFC8520, March 2019,
              <https://www.rfc-editor.org/info/rfc8520>.

   [RFC9334]  Birkholz, H., Thaler, D., Richardson, M., Smith, N., and
              W. Pan, "Remote ATtestation procedureS (RATS)
              Architecture", RFC 9334, DOI 10.17487/RFC9334, January
              2023, <https://www.rfc-editor.org/info/rfc9334>.

   [SEMVER]   Preston-Werner, T., "Semantic Versioning 2.0.0",
              <https://semver.org/spec/v2.0.0.html>.

   [SWID-GUIDANCE]
              Waltermire, D., Cheikes, B. A., Feldman, L., and G. Witte,
              "Guidelines for the Creation of Interoperable Software
              Identification (SWID) Tags", NISTIR 8060, April 2016,
              <https://doi.org/10.6028/NIST.IR.8060>.

   [X.1520]   ITU-T, "Common vulnerabilities and exposures", ITU-T
              Recommendation X.1520, January 2014,
              <https://www.itu.int/rec/T-REC-X.1520>.

Acknowledgments

   This document draws heavily on the concepts defined in the ISO/IEC
   19770-2:2015 specification.  The authors of this document are
   grateful for the prior work of the 19770-2 contributors.

   We are also grateful for the careful reviews provided by the IESG
   reviewers.  Special thanks go to Benjamin Kaduk.

Contributors

   Carsten Bormann
   Universität Bremen TZI
   Postfach 330440
   D-28359 Bremen
   Germany
   Phone: +49-421-218-63921
   Email: cabo@tzi.org


   Carsten Bormann contributed to the CDDL specifications and the IANA
   considerations.

Authors' Addresses

   Henk Birkholz
   Fraunhofer SIT
   Rheinstrasse 75
   64295 Darmstadt
   Germany
   Email: henk.birkholz@sit.fraunhofer.de


   Jessica Fitzgerald-McKay
   National Security Agency
   9800 Savage Road
   Ft. Meade, Maryland 20755
   United States of America
   Email: jmfitz2@cyber.nsa.gov


   Charles Schmidt
   The MITRE Corporation
   202 Burlington Road
   Bedford, Massachusetts 01730
   United States of America
   Email: cmschmidt@mitre.org


   David Waltermire
   National Institute of Standards and Technology
   100 Bureau Drive
   Gaithersburg, Maryland 20877
   United States of America
   Email: david.waltermire@nist.gov