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authorThomas Voss <mail@thomasvoss.com> 2024-11-27 20:54:24 +0100
committerThomas Voss <mail@thomasvoss.com> 2024-11-27 20:54:24 +0100
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+Network Working Group L. Masinter
+Request for Comments: 2534 Xerox Corporation
+Category: Standards Track D. Wing
+ Cisco Systems, Inc.
+ A. Mutz
+ Jutvision Corporation
+ K. Holtman
+ TUE
+ March 1999
+
+
+ Media Features for Display, Print, and Fax
+
+Status of this Memo
+
+ This document specifies an Internet standards track protocol for the
+ Internet community, and requests discussion and suggestions for
+ improvements. Please refer to the current edition of the "Internet
+ Official Protocol Standards" (STD 1) for the standardization state
+ and status of this protocol. Distribution of this memo is unlimited.
+
+Copyright Notice
+
+ Copyright (C) The Internet Society (1999). All Rights Reserved.
+
+Abstract
+
+ This specification defines some common media features for describing
+ image resolution, size, color, and image representation methods that
+ are common to web browsing, printing, and facsimile applications.
+ These features are registered for use within the framework of [REG].
+
+1. Introduction
+
+ This work was originally motivated by the requirements from web
+ browsers to send the browser's display characteristics to the web
+ server to allow the server to choose an appropriate representation.
+
+ This specification defines some common media features [REG] by which
+ a recipient may inform a sender as to the characteristics of its
+ message handling. The sender may then provide the variant of the
+ message that is most suitable for the recipient.
+
+ Different variants would typically be higher or lower resolution
+ images (for example) as appropriate. In the case of a sending to a
+ printer, the result would be higher quality output. In the case of a
+ small screen device (cellphone, portable digital assistant), the
+ result would be faster transmission.
+
+
+
+Masinter, et al. Standards Track [Page 1]
+
+RFC 2534 Media Features for Display, Print, and Fax March 1999
+
+
+ Media features may be used in many different protocol situations.
+ Those defined in this specification can indicate the display or
+ printer dimensions, resolution, color capability. The physical
+ dimensions of a display may be inferred from the display size and
+ display resolution. In the case of paper output, the paper size may
+ be expressed as a token from a list of standard paper sizes. These
+ are presented formally in the Notation section.
+
+2. Media Feature Registrations
+
+ This section defines several media features, using the form specified
+ in [REG].
+
+2.1 Image Size
+
+ - Media Feature tag name(s):
+
+ pix-x
+ pix-y
+
+ - ASN.1 identifier associated with this feature tag:
+
+ 1.3.6.1.8.1.1
+ 1.3.6.1.8.1.2
+
+ - Summary of the media features indicated by this feature tag:
+
+ These features indicate the display size of the recipient for
+ display or print, measured in pixels; they indicate horizontal
+ (pix-x) and vertical (pix-y) dimensions.
+
+ - Values appropriate for use with this feature tag:
+
+ Signed Integer
+
+ - The feature tag is intended primarily for use in the following
+ applications, protocols, services, or negotiation mechanisms:
+
+ Display and print applications where different media choices will
+ be made depending on the size of the recipient device. For
+ example, a web application for use on a 240x480 display might use
+ different HTML pages than one intended for use on a 1024x768
+ display.
+
+
+
+
+
+
+
+
+Masinter, et al. Standards Track [Page 2]
+
+RFC 2534 Media Features for Display, Print, and Fax March 1999
+
+
+2.2 Resolution
+
+ - Media Feature tag name:
+
+ dpi
+
+ - ASN.1 identifier associated with this feature tag:
+
+ 1.3.6.1.8.1.3
+
+ - Summary of the media features indicated by this feature tag:
+
+ This feature indicates the resolution that the recipient can
+ display or print without loss, measured in pixels per inch.
+ Typically resolution capability is represented as dots-per-inch
+ rather than in SI units [SI]. Values for dpi may be expressed as a
+ rational to accomodate resolution of SI-based devices; for example
+ dpi=19558/100 can be used to represent a resolution of 77 dots per
+ centimeter.
+
+ - Values appropriate for use with this feature tag:
+
+ Rational
+
+ - The feature tag is intended primarily for use in the following
+ applications, protocols, services, or negotiation mechanisms:
+
+ Printing and fax applications typically choose representations of
+ a transmitted document depending on the resolution of the
+ recipient rather than pixel size.
+
+ - Examples of typical use:
+
+ Choosing a version of a printable document to send to a printer.
+
+ - Considerations particular to use in individual applications,
+ protocols, services, or negotiation mechanisms:
+
+ Software applications are typically unaware of the resolution of
+ the display. Note that there exist devices with different
+ resolution in different directions, i.e., individual pixels are
+ not square. However, this feature only encompasses the
+ uniform resolution.
+
+
+
+
+
+
+
+
+Masinter, et al. Standards Track [Page 3]
+
+RFC 2534 Media Features for Display, Print, and Fax March 1999
+
+
+2.3 Registration of 'ua-media'
+
+ - Media Feature tag name(s):
+
+ ua-media
+
+ - ASN.1 identifier associated with this feature tag:
+
+ 1.3.6.1.8.1.4
+
+ - Summary of the media features indicated by this feature tag:
+
+ This feature indicates the recipients device media, indicated with
+ an simple token.
+
+ - Values appropriate for use with this feature tag:
+
+ Token with an equality relationship. Values include:
+
+ screen A refreshable display
+ screen-paged a refreshable display which cannot scroll
+ stationery Separately cut sheets of an opaque material
+ transparency Separately cut sheets of a transparent material
+ envelope Envelopes that can be used for conventional
+ mailing purposes
+ envelope-plain Envelopes that are not preprinted and have no
+ windows
+ continuous Continuously connected sheets of an opaque
+ material
+
+ - The feature tag is intended primarily for use in the following
+ applications, protocols, services, or negotiation mechanisms:
+
+ Most of the feature values are useful for printing applications, or
+ to distinguish printing from display.
+
+ - Examples of typical use:
+
+ This might typically be used for selecting between a rendition that
+ is intended to be printed and one that is intended to be displayed.
+
+ - Considerations particular to use in individual applications,
+ protocols, services, or negotiation mechanisms:
+
+ Other media values were not included because their utility seemed
+ relative.
+
+
+
+
+
+Masinter, et al. Standards Track [Page 4]
+
+RFC 2534 Media Features for Display, Print, and Fax March 1999
+
+
+ - Interoperability considerations:
+
+ Interoperability with the Internet Print Protocol means that some
+ additional feature values may need to be registered.
+
+2.4 Paper Size
+
+ - Media Feature tag name(s):
+
+ paper-size
+
+ - ASN.1 identifier associated with this feature tag:
+
+ 1.3.6.1.8.1.5
+
+ - Summary of the media features indicated by this feature tag:
+
+ For stationery, it is often useful to have information about the
+ size of display used. While it is more precise and predictable to
+ use absolute resolution and pixel sizes, some applications find it
+ useful to provide paper size in addition to this information. Note
+ that not all of the paper may have a printable area.
+
+ - Values appropriate for use with this feature tag:
+
+ Token with an equality relationship. Typical values include:
+
+ letter 8.5x11.0 inches
+ a4 210x297 mm
+ b4 250x353 mm
+ a3 297x420 mm
+ legal 8.5x14 inches
+
+ - The feature tag is intended primarily for use in the following
+ applications, protocols, services, or negotiation mechanisms:
+
+ This feature tag seems most useful for the printing application.
+
+ - Examples of typical use:
+
+ Choosing between a4 and letter size renditions of the same
+ printable document.
+
+
+
+
+
+
+
+
+
+Masinter, et al. Standards Track [Page 5]
+
+RFC 2534 Media Features for Display, Print, and Fax March 1999
+
+
+2.5 Color and greyscale
+
+ - Media Feature tag name(s):
+
+ color
+
+ - ASN.1 identifier associated with this feature tag:
+
+ 1.3.6.1.8.1.6
+
+ - Summary of the media features indicated by this feature tag:
+
+ This feature indicates a gross level of capability to represent (or
+ need for) for handling of color, out of a limited set of choices.
+
+ - Values appropriate for use with this feature tag:
+
+ Token with an equality relationship. Values include:
+
+ binary black-and-white, or other bi-level capability.
+
+ grey more than two levels of intensity; for example,
+ at least two bits of grey-scale data
+
+ limited availability of a small number of colors, such as
+ might be provided by a highlight printer, pen plotter,
+ or limited color display. Such capability is useful
+ for business graphics. At the lowest level of
+ capability, this implies at least one color other than
+ black ("highlight color"). At the high end, a small
+ number (less than 32) colors. No implication is made
+ that any particular color is available.
+
+ mapped pixel color values are mapped in some specifable way
+ to a multi-component color space. Sufficient levels of
+ display are available to represent a continuous tone
+ photographic image, but the result will be mapped into
+ a more limited space.
+
+ full ability (or at least willingness) to represent a full
+ color image and present it. Full continuous tone color
+ capability.
+
+ - The feature tag is intended primarily for use in the following
+ applications, protocols, services, or negotiation mechanisms:
+
+
+
+
+
+
+Masinter, et al. Standards Track [Page 6]
+
+RFC 2534 Media Features for Display, Print, and Fax March 1999
+
+
+ Web applications may choose between color, grey, or binary
+ representations. Fax or printing applications might choose between
+ color and non-color renditions, for example.
+
+ - Examples of typical use:
+
+ Someone preparing a map of directions to a restaurant might prepare
+ different maps for each kind of value.
+
+ - Intended usage:
+
+ COMMON
+
+3. Examples of use of features
+
+ The following examples of feature comparison show how these features
+ can be used to describe various capabilities. The syntax used to
+ express combinations of features is purely illustrative and not
+ normative:
+
+ pix-x<=1024, pix-y<=768
+ might be used for a 1024x768 display.
+
+ dpi=300
+ might be used for a 300 dpi printer.
+
+ paper-size=a4
+ indicates the display size is 210x297mm.
+
+4. IANA considerations
+
+ This document calls for registration of the following feature tags,
+ as per [REG]: pix-x, pix-y, dpi, ua-media, paper-size, color. ASN.1
+ identifiers should be assigned to each of these and replaced in the
+ body of the registration.
+
+5. Security Considerations
+
+ Inaccurate media feature information ascribed to a recipient might
+ cause a sender to subsequently send content that the recipient is not
+ actually able to process, thus causing a denial of service.
+
+6. Acknowledgments
+
+ This document is based on a previous memo co-authored with Lou
+ Montoulli. It had benefited from the comments of Graham Klyne, Ho
+ John Lee, Brian Behlendorf, Jeff Mogul, Ted Hardie, and Dan Wing.
+
+
+
+
+Masinter, et al. Standards Track [Page 7]
+
+RFC 2534 Media Features for Display, Print, and Fax March 1999
+
+
+7. References
+
+ [REG] Holtman, K., Mutz, A. and T. Hardie. "Feature Tag Registration
+ Procedures", BCP 31, RFC 2506, March 1999.
+
+ [SI] ISO 1000:1992 "SI units and recommendations for the use of
+ their multiples and of certain other units", International
+ Organization for Standardization, 1992.
+
+Authors' Addresses
+
+ Larry Masinter
+ Xerox Corporation
+ Palo Alto Research Center
+ 3333 Coyote Hill Road
+ Palo Alto CA 94304
+
+ Fax +1 650 812 4333
+ EMail: masinter@parc.xerox.com
+
+
+ Dan Wing
+ Cisco Systems, Inc.
+ 101 Cooper Street
+ Santa Cruz, CA 95060 USA
+
+ Phone: +1 831 457 5200
+ Fax: +1 831 457 5208
+ EMail: dwing@cisco.com
+
+
+ Andrew H. Mutz
+ Jutvision Corporation
+ 124 University Avenue Suite 202
+ Palo Alto CA 94301
+
+ Phone: +1 650 325 6787
+ Fax: +1 650 325 9337
+ Email: mutz@alum.mit.edu
+
+
+ Koen Holtman
+ Technische Universiteit Eindhoven
+ Postbus 513
+ Kamer HG 6.57
+ 5600 MB Eindhoven (The Netherlands)
+
+ EMail: koen@win.tue.nl
+
+
+
+Masinter, et al. Standards Track [Page 8]
+
+RFC 2534 Media Features for Display, Print, and Fax March 1999
+
+
+Full Copyright Statement
+
+ Copyright (C) The Internet Society (1999). All Rights Reserved.
+
+ This document and translations of it may be copied and furnished to
+ others, and derivative works that comment on or otherwise explain it
+ or assist in its implementation may be prepared, copied, published
+ and distributed, in whole or in part, without restriction of any
+ kind, provided that the above copyright notice and this paragraph are
+ included on all such copies and derivative works. However, this
+ document itself may not be modified in any way, such as by removing
+ the copyright notice or references to the Internet Society or other
+ Internet organizations, except as needed for the purpose of
+ developing Internet standards in which case the procedures for
+ copyrights defined in the Internet Standards process must be
+ followed, or as required to translate it into languages other than
+ English.
+
+ The limited permissions granted above are perpetual and will not be
+ revoked by the Internet Society or its successors or assigns.
+
+ This document and the information contained herein is provided on an
+ "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
+ TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
+ BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
+ HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
+ MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
+
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+Masinter, et al. Standards Track [Page 9]
+