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+
+John Day                               Data Entry Terminal Option
+June 27,1977                                            NIC 40652
+                                                          RFC 731
+
+
+
+
+
+
+
+
+                Telnet Data Entry Terminal Option
+
+
+
+1.  Command Name and code:
+
+        DET             20
+
+
+2.  Command Meanings
+
+     IAC WILL DET
+     The sender of this command REQUESTS or AGREES  to  send  and
+     receive subcommands to control the Data Entry Terminal.
+
+     IAC WONT DET
+     The sender of this  command  REFUSES  to  send  and  receive
+     subcommands to control the Data Entry Terminal.
+
+     IAC DO DET
+     The sender of this command REQUESTS or AGREES  to  send  and
+     receive subcommands to control the Data Entry Terminal.
+
+     IAC DONT DET
+     The sender of this  command  REFUSES  to  send  and  receive
+     subcommands to control the Data Entry Terminal.
+
+     The DET option  uses  five  classes  of  subcommands  1)  to
+     establish   the   requirements   and   capabilities  of  the
+     application and the terminal, 2) to format the  screen,  and
+     to  control  the  3)  edit,  4) erasure, and 5) transmission
+     functions.  The subcommands that perform these functions are
+     described below.
+
+
+     T__h_e_N__e_t_w_o_r_k_V__i_r_t_u_a_l_D__a_t_a_E__n_t_r_y_T__e_r_m_i_n_a_l(NVDET)
+
+        The NVDET  consists  of  a  keyboard  and  a  rectangular
+        display.   The  keyboard  is capable of generating all of
+        the characters of the ASCII character set.  In  addition,
+        the  keyboard may possess a number of function keys which
+        when pressed cause a FN subcommand to be sent.  (Although
+        most DET's will support one or  more  peripheral  devices
+        such  as  a  paper  tape reader or a printer, this option
+
+
+                                1
+
+John Day                               Data Entry Terminal Option
+June 27,1977                                            NIC 40652
+                                                          RFC 731
+
+
+        does not consider their support.  Support  of  peripheral
+        devices should be treated by a separate option.)
+
+        The screen of the data entry terminal is  a  rectangle  M
+        characters  by N lines.  The values of M and N are set by
+        negotiating the Output Line Width and  Output  Page  Size
+        options,  respectively.   The next writing position (x,y)
+        on the screen (where x is the character position and y is
+        the position of the line on the screen) is indicated by a
+        special display character called the cursor.  The  cursor
+        may  be  moved  to  any  position  on  the screen without
+        disturbing any characters already on the screen.   Cursor
+        addressing   in   existing   terminals  utilizes  several
+        topologies and addressing methods.  In order to make  the
+        burden of implementaton as easy as possible this protocol
+        supports two topologies (the finite plane and the helical
+        torus)  and three addressing methods ((x,y); x and y, and
+        relative  increments).   Since  the  finite  plane   with
+        absolute  addressing  is  the  least  ambiguous  and  the
+        easiest to translate to and from the others,  it  is  the
+        default scheme used by the NVDET.  The torodial form with
+        either  relative  or  absolute addressing is provided for
+        convience.
+
+        Also  the NVDET provides a mechanism for defining on  the
+        screen  fields  with  special  attributes.   For example,
+        characters entered into these  fields  may  be  displayed
+        with  brighter intensity, highlighted by reverse video or
+        blinking, or protected from  modification  by  the  user.
+        This  latter  feature is one of the most heavily used for
+        applications where the DET displays a form to  be  filled
+        out by the user.
+
+        The  definition  of  the   NVDET   uses   Telnet   option
+        subnegotiations  to  accomplish  all  of  its  functions.
+        Since none of the  ASCII  characters  sent  in  the  data
+        stream  have been used to define these functions, the DET
+        option can be used in a "raw" or even  "rare"  mode.   In
+        circumstances  where  the  application program knows what
+        kind of terminal is on the other end,  it  can  send  the
+        ASCII   characters  required  to  control  functions  not
+        supported by the option or an implementation.  In general
+        keeping all  NVDET  functions  out  of  the  data  stream
+        provides better flexibility.
+
+     F__a_c_i_l_i_t_y_F__u_n_c_t_i_o_n_s  (for detailed semantics see Section 5.)
+
+     IAC SB DET <DET facility subcommand><facility map> IAC SE
+
+        where  <DET  facility  subcommand>  is  one  8-bit   byte
+
+
+                                2
+
+John Day                               Data Entry Terminal Option
+June 27,1977                                            NIC 40652
+                                                          RFC 731
+
+
+        indicating  the  class of the facilities to be described,
+        and <facility map> is a field of one or two  8-bit  bytes
+        containing  flags  describing  the facilities required or
+        desired by the sender.  The bits of the facility maps are
+        numbered from the right starting at zero.  Thus, if bit 2
+        is set the field will have a decimal  value  of  4.   The
+        values of the field are as follows:
+
+        facility cmd:  EDIT FACILITIES     subcommand code: 1
+          facility map:                              bit numbers
+             Toroidal Cursor Addressing                  6
+             Incremental Cursor Addressing               5
+             Read Cursor Address                         4
+             Line Insert/Delete                          3
+             Char Insert/Delete                          2
+             Back Tab                                    1
+             Positive Addressing only                    0
+
+        where:
+
+        If the Toroidal Cursor Addressing bit is set, the  sender
+        requests  or  provides  that the SKIP TO LINE and SKIP TO
+        CHAR subcommands be supported.
+
+        If the Incremental Cursor  Addressing  bit  is  set,  the
+        sender  requests or provides that the UP, DOWN, LEFT, and
+        RIGHT subcommands be supported.
+
+        If the Read Cursor bit is set,  the  sender  requests  or
+        provides the READ CURSOR subcommand.
+
+        If the Line Insert/Delete bit is set, the sender requests
+        or  provides  that  the  LINE  INSERT  and  LINE   DELETE
+        subcommands be supported.
+
+        If the Char Insert/Delete bit is set, the sender requests
+        or  provides  that  the  CHAR  INSERT  and  CHAR   DELETE
+        subcommands be supported.
+
+        If the Back Tab  bit  is  set,  the  sender  requests  or
+        provides that the BACK TAB subcommand be supported.
+
+        If the Positive Addressing bit is set, then the sender is
+        informing the receiver that it can only move  the  cursor
+        in  the  positive direction.  (Note:  Terminals that have
+        this property also have a Home function to  get  back  to
+        the beginning.)
+
+        facility cmd:  ERASE FACILITIES     subcommand code:  2
+          facility map:                                bit numbers
+
+
+                                3
+
+John Day                               Data Entry Terminal Option
+June 27,1977                                            NIC 40652
+                                                          RFC 731
+
+
+             Erase Field                                     4
+             Erase Line                                      3
+             Erase Rest of Screen                            2
+             Erase Rest of Line                              1
+             Erase Rest of Field                             0
+
+        where:
+
+        If a bit of the facility map for this facility command is
+        set,  the  sender  requests  or  provides  the   facility
+        indicated by the bit.  For a more complete description of
+        each  of  these functions see the Erase Functions section
+        below.
+
+        facility cmd:  TRANSMIT FACILITIES     subcommand code:  3
+          facility map:                      bit numbers
+             Data Transmit                         5
+             Transmit Line                         4
+             Transmit Field                        3
+             Transmit Rest of Screen               2
+             Transmit Rest of Line                 1
+             Transmit Rest of Field                0
+
+        where:
+
+        If a bit of the facility map for this facility command is
+        set,  the  sender  requests  or  provides  the   facility
+        indicated by the bit.  For a more complete description of
+        each  of  these  functions  see  the  Transmit  Functions
+        section below.
+
+        facility cmd:  FORMAT FACILITIES     subcommand code:  4
+          facility map:                               bit numbers
+                                        byte 0
+             Repeat                                         4
+             Blinking                                       3
+             Reverse Video                                  2
+             Right Justification                            1
+             Overstrike                                     0
+
+                                        byte 1
+             Protection On/Off                              6
+             Protection                                     5
+             Alphabetic-only Protection                     4
+             Numeric-only Protection                        3
+             Intensity                                      0-2
+
+        where:
+
+        If the Repeat bit is set the sender requests or  provides
+
+
+                                4
+
+John Day                               Data Entry Terminal Option
+June 27,1977                                            NIC 40652
+                                                          RFC 731
+
+
+        the REPEAT subcommand.
+
+        If the Blinking  bit  is  set,  the  sender  requests  or
+        provides  the ability to highlight a string of characters
+        by causing them to blink.
+
+        If the Reverse Video bit is set, the sender  requests  or
+        provides  the ability to highlight a string of characters
+        by "reversing the video image," i.e., if  the  characters
+        are  normally  displayed  as  black characters on a white
+        background, this is reversed to be white characters on  a
+        black background, or vice versa.
+
+        If  the  Right  Justification  bit  is  set,  the  sender
+        requests or provides the ability to cause entries of data
+        to be right justified in the field.
+
+        If the Overstrike bit is  set,  the  sender  requests  or
+        provides  the  ability  to superimpose one character over
+        another on the screen much  like  a  hard  copy  terminal
+        would  do if the print mechanism struck the same position
+        on the paper with different characters.
+
+        If the Protection On/Off bit is set, the sender  requests
+        or  provides  the  ability  to  turn  on  and  off  field
+        protection.
+
+        If the Protection bit is  set,  the  sender  requests  or
+        provides  the  ability  to  protect  certain  strings  of
+        characters displayed on the screen from being altered  by
+        the  user of the terminal.  Setting this bit also implies
+        that   ERASE   UNPROTECTED   and   TRANSMIT   UNPROTECTED
+        subcommands (see below) are supported.
+
+        If the Alphabetic-only Protection bit is set, the  sender
+        requests or provides the ability to constrain the user of
+        the  terminal such that he may only enter alphabetic data
+        into certain areas of the screen.
+
+        If the Numeric-only Protection bit  is  set,  the  sender
+        requests or provides the ability to constrain the user of
+        the  terminal  such that he may only enter numerical data
+        into certain areas of the screen.
+
+        The three bits of the  Intensity  field  will  contain  a
+        positive  binary  integer indicating the number of levels
+        of intensity that the sender  requests  or  provides  for
+        displaying the data.  The value of the 3 bit field should
+        be interpreted in the following way:
+
+
+
+                                5
+
+John Day                               Data Entry Terminal Option
+June 27,1977                                            NIC 40652
+                                                          RFC 731
+
+
+           1        one visible intensity
+           2        two intensities; normal and bright
+           3        three intensities; off, normal, and bright
+          >3        >3 intensities; off, and the remaining levels
+                    proportioned from dimmest to brightest intensity.
+
+        For the all of the above commands, if the appropriate bit
+        in <facility map> is not set, then the  sender  does  not
+        request or provide that facility.
+
+
+     E__d_i_t_i_n_g_F__u_n_c_t_i_o_n_s
+
+        IAC SB DET MOVE CURSOR <x><y> IAC SE  subcommand code: 5
+
+        where <x> is an 8-bit byte containing a  positive  binary
+        integer   representing  the  character  position  of  the
+        cursor, <y> is an 8-bit byte containing a positive binary
+        integer representing the line position of the cursor.
+
+        This subcommand moves the cursor to the  absolute  screen
+        address (x,y) with the following boundary conditions:
+
+          if x>M-1, set x=M-1 and send an ERROR subcommand
+          if y>N-1, set y=N-1 and send an  ERROR subcommand
+
+        This describes a finite plane topology on the screen.
+
+        IAC SB DET SKIP TO LINE <y> IAC SE    subcommand code: 6
+
+        where <y> is a positive 8-bit binary number.
+
+        This subcommand moves the cursor to the  absolute  screen
+        line y.  x remains constant.  For values of y>N-1
+          y = y mod N.
+
+        IAC SB DET SKIP TO CHAR <x> IAC SE   subcommand code: 7
+
+        where <x> is a positive 8-bit binary number.
+
+        This  subcommand  moves  the  cursor  to   the   absolute
+        character  position  x.  y remains constant, unless x>M-1
+        in which case:
+          x' = (x mod M)
+          y' = (y+(x DIV N))
+          where x' and y' are the new values of  the cursor.
+
+        These last two subcommands define a toroidal topology  on
+        the screen.
+
+
+
+                                6
+
+John Day                               Data Entry Terminal Option
+June 27,1977                                            NIC 40652
+                                                          RFC 731
+
+
+        IAC SB DET UP IAC SE            subcommand code:  8
+        IAC SB DET DOWN IAC SE          subcommand code:  9
+        IAC SB DET LEFT IAC SE          subcommand code: 10
+        IAC SB DET RIGHT IAC SE         subcommand code: 11
+
+        These subcommands are provided as a convenience for  some
+        terminals.   The  commands  UP, DOWN, LEFT, and RIGHT are
+        defined as
+
+        UP:         (x,y)=(x, y-1 mod N)
+        DOWN:       (x,y)=(x, y+1 mod N)
+        LEFT:       (x,y)=(x-1, y); if x=0 then x-1 = 0
+        RIGHT:      (x,y)=(x+1 mod M, y) and y = y+1 if x+1>M-1
+
+        Note:  DOWN, LEFT, and RIGHT cannot always be replaced by
+        the  ASCII  codes  for  linefeed,  backspace,  and  space
+        respectively.   The latter are format effectors while the
+        former are cursor controls.
+
+        IAC SB DET HOME IAC SE      subcommand code:  12
+
+        This subcommand positions the cursor to (0,0).   This  is
+        equivalent  to  a MOVE CURSOR 0,0 or the sequence SKIP TO
+        LINE 0, SKIP TO CHAR 0.  This subcommand is provided  for
+        convenience,  since  most terminals have it as a separate
+        control.
+
+        IAC SB DET LINE INSERT IAC SE     subcommand code:  13
+
+        This subcommand inserts a line of spaces between lines  y
+        (the  current  line,  determined  by  the position of the
+        cursor) and line y-1.  Lines y through N-2 move down  one
+        line,  i.e.  line  y  becomes line y+1;  y+1 becomes y+2,
+        ...; N-2 becomes N-1.  Line N-1 is lost off the bottom of
+        the  screen.   The  position  of   the   cursor   remains
+        unchanged.
+
+        IAC SB DET LINE DELETE IAC SE     subcommand code:  14
+
+        This subcommand deletes line y where  y  is  the  current
+        line  position of the cursor.  Lines y+1 through N-1 move
+        up one line, i.e.  line y+1 becomes line y;  y+2  becomes
+        y+1;  ...;  N-1  becomes N-2.  The N-1st line position is
+        set  to  all  spaces.   The   cursor   position   remains
+        unchanged.
+
+        IAC SB DET CHAR INSERT IAC SE     subcommand code: 15
+
+        This subcommand inserts the next character  in  the  data
+        stream  between  the xth and x-1st characters, where x is
+
+
+                                7
+
+John Day                               Data Entry Terminal Option
+June 27,1977                                            NIC 40652
+                                                          RFC 731
+
+
+        the current character position of the  cursor.   The  xth
+        through  M-2nd  characters  on  the  line are shifted one
+        character positon to the right.   The  new  character  is
+        inserted   at   the  vacated  xth  position.   The  M-1st
+        character is lost.  The position of  the  cursor  remains
+        unchanged.
+
+        IAC SB DET CHAR DELETE IAC SE     subcommand code:  16
+
+        This subcommand deletes the character on  the  screen  at
+        the x-th position.  The x-th character is removed and the
+        characters  x+1  through  M-1  are  shifted one character
+        position to the left to become  the  x-th  through  M-2nd
+        characters.   The M-1st character position is left empty.
+        (For most terminals it will be set to a  NUL  or  space.)
+        The cursor position remains unchanged.
+
+        IAC SB DET READ CURSOR IAC SE     subcommand code:  17
+
+        This subcommand requests the receiver to send the present
+        position of the cursor to the sender.
+
+        IAC SB DET CURSOR POSITION <x><y> IAC SE
+                                          subcommand code:  18
+
+        where <x> and <y> are positive 8-bit binary integers.
+
+        This subcommand is sent by  a  Telnet  implementation  in
+        response  to  a  READ  CURSOR  subcommand  to  convey the
+        coordinates of the cursor to the other side.  Note: x  is
+        less than  M and y is less than  N.
+
+        IAC  SB DET REVERSE TAB IAC SE     subcommand code:  19
+
+        This subcommand causes the cursor to move to the previous
+        tab position.  If none exists on the  present  line,  the
+        cursor  moves  to the previous line and so on until a tab
+        is found or the address (0,0) is encountered.  When field
+        protection is in effect the cursor moves to the beginning
+        of the preceding unprotected field.
+
+     T__r_a_n_s_m_i_t_F__u_n_c_t_i_o_n_s  (For detailed semantics see Section 5.)
+
+        IAC SB DET TRANSMIT SCREEN IAC SE     subcommand code: 20
+
+        This subcommand  causes  the  terminal  to  transmit  all
+        characters   on   the   screen  from  position  (0,0)  to
+        (M-1,N-1).   The  cursor  will  be  at  (0,0)  after  the
+        operation is complete.
+
+
+
+                                8
+
+John Day                               Data Entry Terminal Option
+June 27,1977                                            NIC 40652
+                                                          RFC 731
+
+
+        IAC SB DET TRANSMIT UNPROTECTED IAC SE
+                                        subcommand code:  21
+
+        This subcommand  causes  the  terminal  to  transmit  all
+        characters  in  unprotected fields from position (0,0) to
+        (M-1,N-1).  The unprotected fields are separated  by  the
+        field  separator subcommand.  The cursor will be at (0,0)
+        or at the beginning of the first unprotected field  after
+        the operation is complete.
+
+        IAC SB DET TRANSMIT LINE IAC SE      subcommand code:  22
+
+        This subcommand causes the terminal to transmit all  data
+        on  the  yth  line  where  y is determined by the present
+        position of the cursor.   Data  is  sent  from  character
+        position  (0,y)  to  the  end-of-line or position (M-1,y)
+        whichever comes first.  The  cursor  position  after  the
+        transmission  is  one character position after the end of
+        line  condition  or  the  beginning  of  the  next  line,
+        (0,y+1).
+
+        IAC SB DET TRANSMIT FIELD IAC SE     subcommand code:  23
+
+        This subcommand causes the terminal to transmit all  data
+        in  the  field  presently  occupied  by  the cursor.  The
+        cursor position after the operation is  complete  is  one
+        character position after the end of the field or, if that
+        position  is  protected,  at  the  beginning  of the next
+        unprotected field.
+
+        IAC SB DET TRANSMIT REST OF SCREEN IAC SE
+                                        subcommand code:  24
+
+        This subcommand  causes  the  terminal  to  transmit  all
+        characters on the screen from position (x,y) to (M-1,N-1)
+        or  until  the end of text.   (x,y) is the current cursor
+        position.  The cursor position after the operation is one
+        character position after  the  last  text  character,  or
+        (0,0) if the last filled character position is (M-1,N-1).
+
+        IAC SB DET TRANSMIT REST OF LINE IAC SE
+                                        subcommand code:  25
+
+        This subcommand  causes  the  terminal  to  transmit  all
+        characters on the yth line from position (x,y) to the end
+        of  line  or (M-1,y) whichever comes first.  (x,y) is the
+        current cursor position.  The cursor position  after  the
+        operation  is  one  character  position  after  the  last
+        character of the line or the first character of the  next
+        line.
+
+
+                                9
+
+John Day                               Data Entry Terminal Option
+June 27,1977                                            NIC 40652
+                                                          RFC 731
+
+
+
+        IAC SB DET TRANSMIT REST OF FIELD IAC SE
+                                        subcommand code:  26
+
+        This subcommand causes the receiver to transmit the  rest
+        of  the characters in the field currently occupied by the
+        cursor.  The cursor position after the  operation  is  at
+        the beginning of the next field.
+
+        IAC SB DET DATA TRANSMIT <x><y> IAC SE
+                                        subcommand code:  27
+
+        This subcommand is used to preface  data  sent  from  the
+        terminal  in  response  to  a  user  action or a TRANSMIT
+        command.  The parameters <x> and <y> indicate the initial
+        position of the cursor.   See  the  Transmit  Subcommands
+        subsection in Section 5 for more details.
+
+
+     E__r_a_s_e_F__u_n_c_t_i_o_n_s
+
+        IAC SB DET ERASE SCREEN IAC SE     subcommand code: 28
+
+        This subcommand causes all characters to be removed  from
+        the  screen.   All  fields regardless of their attributes
+        are deleted.  The cursor  position  after  the  operation
+        will  be (0,0).  Most terminals set the erased characters
+        to either NUL or space characters.
+
+        IAC SB DET ERASE LINE IAC SE     subcommand code:  29
+
+        This subcommand causes all characters on the yth line  to
+        be  removed  from  the screen, where y is the line of the
+        current cursor position.  All fields regardless of  their
+        attributes  are  deleted.  The cursor position after this
+        operation will be (0,y).  Note:  This  operation  can  be
+        easily  simulated  by  the  sequence:   LINE DELETE, LINE
+        INSERT.  However, the order is important to  insure  that
+        no data is lost off the bottom of the screen.
+
+        IAC SB DET ERASE FIELD IAC SE     subcommand code:  30
+
+        This  subcommand  causes  all  characters  in  the  field
+        occupied  by  the  cursor  to  be  removed.   The  cursor
+        position after the operation is at the beginning  of  the
+        field.
+
+        IAC SB DET ERASE REST OF SCREEN IAC SE
+                                        subcommand code:  31
+
+
+
+                               10
+
+John Day                               Data Entry Terminal Option
+June 27,1977                                            NIC 40652
+                                                          RFC 731
+
+
+        This subcommand causes all characters from position (x,y)
+        to (M-1,N-1) to be removed from the screen.   All  fields
+        regardless  of  their attributes are deleted.  The cursor
+        position after  the  operation  is  unchanged.   This  is
+        equivalent  to  doing  an  ERASE REST OF LINE plus a LINE
+        DELETE for lines greater than y.
+
+        IAC SB DET ERASE REST OF LINE IAC SE
+                                        subcommand code:  32
+
+        This subcommand causes all characters from position (x,y)
+        to (M-1,y) to be  removed  from  the  screen  All  fields
+        regardless  of  their attributes are deleted.  The cursor
+        position after the operation is unchanged.
+
+        IAC SB DET ERASE REST OF FIELD IAC SE
+                                        subcommand code:  33
+
+        This subcommand causes all characters from position (x,y)
+        to the end of the current field to be  removed  from  the
+        screen.   The  cursor  position  after  the  operation is
+        unchanged.
+
+        IAC SB DET ERASE UNPROTECTED IAC SE
+                                        subcommand code:  34
+
+        This subcommand causes all characters on  the  screen  in
+        unprotected  fields  to  be removed from the screen.  The
+        cursor position after the operation is at  (0,0)  or,  if
+        that position is protected, at the beginning of the first
+        unprotected field.
+
+     F__o_r_m_a_t_F__u_n_c_t_i_o_n_s
+
+        IAC SB DET FORMAT DATA <format map><count> IAC SE
+                                        subcommand code:  35
+
+        where <format  map>  is  an  8-bit  byte  containing  the
+        following flags:
+
+          Blinking                                 7
+          Reverse Video                            6
+          Right Justification                      5
+          Protection                              3-4
+          Intensity                               0-2
+
+        where:
+
+        If the Blinking  bit  is  set,  the  following  field  of
+        <count>  characters  should  have  the Blinking attribute
+
+
+                               11
+
+John Day                               Data Entry Terminal Option
+June 27,1977                                            NIC 40652
+                                                          RFC 731
+
+
+        applied  to it by the receiver.
+
+        If the Reverse Video bit is set, the following  field  of
+        <count>  characters  should  be displayed by the receiver
+        with video reversed.
+
+        If the Right Justification bit is set, the input  entered
+        into  the  field  of  <count>  characters should be right
+        justified.
+
+        The Protection field is two bits wide and may take on the
+        following values:
+
+          0         no protection
+          1         protected
+          2         alphabetic only
+          3         numeric only
+
+        The protection attribute specifies that  the  other  side
+        may  modify  any  character  (no  protection),  modify no
+        characters   (protected),   enter    only    alphabetical
+        characters  (A-Z,  and  a-z)  (alphabetic only), or enter
+        only numerical characters (0-9,+,.,and -) (numeric  only)
+        in the following field of <count> bytes.
+
+        The  Intensity  field  is  3  bits  wide  and  should  be
+        interpreted in the following way:
+
+        The values 0-6 should be used as  an  indication  of  the
+        relative  brightness  to  be  used  when  displaying  the
+        characters in or entered into the following field <count>
+        characters wide.  The  number  of  levels  of  brightness
+        available  should  have  been  obtained previously by the
+        Format Facility  subcommand.   The  exact  algorithm  for
+        mapping these values to the available levels of intensity
+        is  left  to  the  implementors.   A  value  of  7 in the
+        intensity field indicates that the brightness  should  be
+        off,  and  any  characters  in  or entered into the field
+        should not be displayed.
+
+        <count> is 2  bytes  that  should  be  interpreted  as  a
+        positive 16-bit binary integer representing the number of
+        characters  following  this command which are affected by
+        it.
+
+        Data sent to the terminal or the Using Host for unwritten
+        areas of the screen not in the scope of the count  should
+        be  displayed  with the default values of the format map.
+        The default values are  No  Blinking,  Normal  Video,  No
+        Justification, No Protection and Normal Intensity.
+
+
+                               12
+
+John Day                               Data Entry Terminal Option
+June 27,1977                                            NIC 40652
+                                                          RFC 731
+
+
+
+        This subcommand is used to format data to be displayed on
+        the screen of the terminal.  The <format  map>  describes
+        the  attributes  that the field <count> bytes wide should
+        have.  This field is to start  at  the  position  of  the
+        cursor  when the command is acted upon.  The next <count>
+        displayable characters in the data  stream  are  used  to
+        fill  the  field.   Subsequent  REPEAT subcommands may be
+        used to specify the  contents  of  this  field.   If  the
+        sender  specifies  attributes  that  have not been agreed
+        upon by the use of the Format  Facility  subcommand,  the
+        Telnet  process  should  send  an Error Subcommand to the
+        sender, but format the screen as if the bit had not  been
+        set.
+
+        IAC SB DET REPEAT <count><char> IAC SE
+                                        subcommand code:  36
+
+        where  <count>  is  a  positive  8-bit  binary   integer.
+        <char> is an 8-bit byte containing an ASCII character.
+
+        This subcommand is used to perform  data  compression  on
+        data  being  transferred  to  the  terminal  by  encoding
+        strings of identical characters as the  character  and  a
+        count.   The  repeated  characters may be part of a field
+        specified
+
+        IAC SB DET SUPPRESS PROTECTION <negotiation> IAC SE
+                                            subcommand code:  37
+
+        where <negotiation> may have the  values  of  the  Telnet
+        option negotiation:
+
+                    251                 WILL
+                    252                 WONT
+                    253                 DO
+                    254                 DONT
+
+        This subcommand is used to suppress the field  protection
+        in  a  non-destructive manner.  Many data entry terminals
+        provide the means by which protection may  be  turned  on
+        and  off  without modifying the contents of the screen or
+        the terminal's  memory.   Thus,  the  protection  may  be
+        turned  off  and back on without retransmitting the form.
+        The default setting of the option is that  protection  is
+        on, in other words
+
+                    IAC SB DET SUPPRESS PROTECTION WONT IAC SE
+                    IAC SB DET SUPPRESS PROTECTION DONT IAC SE
+
+
+
+                               13
+
+John Day                               Data Entry Terminal Option
+June 27,1977                                            NIC 40652
+                                                          RFC 731
+
+
+        Negotiation of this subcommand follows the same rules  as
+        negotiations of the Telnet options.
+
+        IAC SB DET FIELD SEPARATOR IAC SE    subcommand code:  38
+
+        It is necessary when transmitting  only  the  unprotected
+        portion  of  the screen to provide a means for delimiting
+        the fields.   Existing  DET's  use  a  variety  of  ASCII
+        characters  such as Tab, Group Separator, Unit Separator,
+        etc.  In order to maintain transparency of the NVDET this
+        subcommand is used to separate the fields.  Clearly, this
+        incurs  rather  high  overhead.   This  overhead  can  be
+        avoided by using the Byte Macro Option (see Appendix 3).
+
+     M__i_s_c_e_l_l_a_n_e_o_u_s_C__o_m_m_a_n_d_s
+
+        IAC SB DET FN <code> IAC SE     subcommand code:  39
+
+        where:  <code> is one byte.
+
+        Many data-entry terminals provide  a  set  of  "function"
+        keys  which  when pressed send a one-character command to
+        the server.  This subcommand describes such  a  facility.
+        The  values  of  the <code> field are defined by the user
+        and server.  The option  merely  provides  the  means  to
+        transfer the information.
+
+        IAC SB DET ERROR <cmd> <error code> IAC SE
+                                        subcommand code:  40
+
+        where:
+               <cmd> is a byte containing the subcommand code  of
+        the subcommand in error.
+                <error code> is a byte containing an error  code.
+        (For a list of the defined error codes see Appendix 2.)
+
+        This  subcommand  is   provided  to  allow   DET   option
+        implementations  to  report  errors  they  detect  to the
+        corresponding Telnet process.  At this point it is  worth
+        reiterating  that  the  philosophy of this option is that
+        when an error is detected it should be reported; however,
+        the implementation should  attempt  its  best  effort  to
+        carry out the intent of the subcommand or data in error.
+
+
+
+
+
+
+
+
+
+                               14
+
+John Day                               Data Entry Terminal Option
+June 27,1977                                            NIC 40652
+                                                          RFC 731
+
+
+3.  Default and Minimal Implementation Specifications
+
+     D__e_f_a_u_l_t
+
+        WON'T DET -- DON'T DET
+
+        Neither host wishes to use the Data Entry Terminal option.
+
+     M__i_n_i_m_a_l_I__m_p_l_e_m_e_n_t_a_t_i_o_n
+
+          DET EDIT FACILITIES
+          DET ERASE FACILITIES
+          DET TRANSMIT FACILITIES
+          DET FORMAT FACILITIES
+          DET MOVE CURSOR <x><y>
+          DET HOME
+          DET ERASE SCREEN
+          DET TRANSMIT SCREEN
+          DET FORMAT DATA
+          DET ERROR <cmd> <error code>
+
+        In  the  case  of  formatting  the  data,   the   minimal
+        implementation  should  be able to support a low and high
+        level  of  intensity  and  protection  for  all   or   no
+        characters in a field.  These functions, however, are not
+        required.
+
+        The minimal implementation also requires that the  Output
+        Line  Width  and  Output  Page  Size  Telnet  options  be
+        supported.
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+                               15
+
+John Day                               Data Entry Terminal Option
+June 27,1977                                            NIC 40652
+                                                          RFC 731
+
+
+4.  Motivation
+
+     The Telnet protocol was originally  designed  to  provide  a
+     means  for  scroll-mode  terminals,  such  as  the  standard
+     teletype, to communicate with processes through the network.
+     This was suitable for the vast  majority  of  terminals  and
+     users  at  that  time.   However,  as use of the network has
+     increased into  other  areas,  especially  areas  where  the
+     network  is  considered  to provide a production environment
+     for other work, the desires and  requirements  of  the  user
+     community  have  changed.   Therefore,  it  is  necessary to
+     consider  supporting  facilities  that  were  not  initially
+     supported.   This  Telnet  option  attempts  to  do that for
+     applications that require data entry terminals.
+
+     This option in effect defines the Network Virtual Data Entry
+     Terminal.  Although the description of this option is  quite
+     long, this does not imply that the Telnet protocol is a poor
+     vehicle  for this facility.  Data Entry Terminals are rather
+     complex and varied in their abilities.  This option attempts
+     to support both the minimal set of useful functions that are
+     either common to all or can be easily simulated and the more
+     sophisticated functions supplied in some terminals.
+
+     Unlike most real data entry  terminals  where  the  terminal
+     functions  are  encoded  into  one or more characters of the
+     native character set, this option performs all such controls
+     within the Telnet  subnegotiation  mechanism.   This  allows
+     programs  that  are  intimately  familiar  with  the kind of
+     terminal they are communicating with to send  commands  that
+     may   not   be   supported  by  either  the  option  or  the
+     implementation.  In other words, it is possible  to  operate
+     in  a  "raw"  or  at  least "rare" mode using as much of the
+     option as necessary.
+
+     Although many data entry  terminals  support  a  variety  of
+     peripheral  devices such as printers, cassettes, etc.  it is
+     beyond  the  scope  of  this  option   to   entertain   such
+     considerations.   A  separate  option  should  be defined to
+     handle this aspect of these devices.
+
+
+
+
+
+
+
+
+
+
+
+
+                               16
+
+John Day                               Data Entry Terminal Option
+June 27,1977                                            NIC 40652
+                                                          RFC 731
+
+
+5.  Description
+
+
+
+G__e_n_e_r_a_l_N__o_t_e_s
+
+     All implementations of this option are required to support a
+     certain minimal set of  the  subcommands  for  this  option.
+     Section  3  contains  a  complete list of the subcommands in
+     this minimal set.   In  keeping  with  the  Telnet  protocol
+     philosophy that an implementation should not have to be able
+     to parse commands it does not implement, every subcommand of
+     this  option  is  either in the minimal set or is covered by
+     one of the facility  subcommands.   An  implementation  must
+     "negotiate"  with  its  correspondent  for permission to use
+     subcommands not in the minimal set before using  them.   For
+     details of this negotiation process see the section below on
+     facility subcommands.
+
+     Most data entry terminals are used in a  half  duplex  mode.
+     (Although  most  DET's  on  the market can be used either as
+     data entry terminals or as standard  interactive  terminals,
+     we  are  only concerned here with their use as DET's.)  When
+     this option is used, it  is  suggested  that  the  following
+     Telnet   options   be   refused:   Echo,  Remote  Controlled
+     Transmission and Echoing, and Suppress  Go-Ahead.   However,
+     this  option  could  be used to support a simple full duplex
+     CRT  based  application  using  the  basic  cursor   control
+     functions  provided  here.   For these cases, one or more of
+     the above list of  options might be required.   (Support  of
+     sophisticated   interactive   calligraphic  applications  is
+     beyond the scope of this   option  and  should  be  done  by
+     another option or the Network Graphics Protocol.)
+
+     In RFC 728, it was noted that a  synch  sequence  can  cause
+     undesired  interactions between Telnet Control functions and
+     the data stream.  A  synch  sequence  causes  data  but  not
+     control  functions  to  be  flushed.   If a control function
+     which has an effect on the  data immediately following it is
+     present in the data stream when a synch sequence occurs, the
+     control function will have its effect not  on  the  intended
+     data  but  on  the data immediately following the Data Mark.
+     The  following  DET  subcommands  are  susceptible  to  this
+     pitfall:
+
+                    CHAR INSERT
+                    DATA TRANSMIT
+                    FORMAT DATA
+
+     The undesired interactions are best avoided by the  receiver
+
+
+                               17
+
+John Day                               Data Entry Terminal Option
+June 27,1977                                            NIC 40652
+                                                          RFC 731
+
+
+     of  the  synch  sequence  deleting these subcommands and all
+     data associated with them before continuing to  process  the
+     control  functions.   This implies that the Data Mark should
+     not occur in the middle of the data  associated  with  these
+     subcommands.
+
+F__a_c_i_l_i_t_y_S__u_b_c_o_m_m_a_n_d_s
+
+     These four subcommands are  used  by  the  User  and  Server
+     implementations  to negotiate the subcommands and attributes
+     of the terminal that may be utilized.  This negotiation  can
+     be  viewed  as  the  terminal  (User  Host)  indicating what
+     facilities are provided and the Server Host (or  application
+     program) indicating what facilities are desired.
+
+     W__h_e_n_S__e_n_t:_  A Server Telnet  implementation  using  the  DET
+     option must send a facility subcommand requesting the use of
+     a  particular  subcommand  or  terminal attribute not in the
+     minimal  implementation  before  the  first  use   of   that
+     subcommand  or  attribute.   The  User Telnet implementation
+     should respond  as  quickly  as  possible  with  its  reply.
+     Neither  the  User  nor Server are required to negotiate one
+     subcommand  at  a  time.   Also,  a  Telnet   implementation
+     responding  to a facility subcommand is not required to give
+     permission only for that subcommand.   It may send a  format
+     map  indicating  all  facilities  of  that  class  which  it
+     supports.   However,  a  Telnet  implementation   requesting
+     facilities  must send a facility subcommand before its first
+     use  of  the  subcommand  regardless  of   whether   earlier
+     negotiations  have  indicated the facility is provided.  The
+     facility cannot  be  used  until  a  corresponding  facility
+     subcommand   has   been   received.    There  are  no  other
+     constraints on when the facility subcommands  may  be  sent.
+     In  particular,  it  is  not necessary for an application to
+     know at the beginning of a session all  facilities  that  it
+     will use.
+
+     A__c_t_i_o_n_W__h_e_n_R__e_c_i_e_v_e_d:_  There are two possible  actions  that
+     may   be  taken  when  a  facility  subcommand  is  received
+     depending on whether  the  receiver  is  a  requestor  or  a
+     provider (User).
+
+     Requestor:  When a facility  subcommand  is  received  by  a
+     requestor  and it is in the state of Waiting for a Reply, it
+     should go into the state of Not  Waiting.   It  should  then
+     take  the  facility  map   it  had sent and form the logical
+     intersection with  the  facility  map  received.   (For  the
+     Intensity  attribute,  one  should  take  the minimum of the
+     number received  and  the  number  requested.)   The  result
+     indicates  the facilities successfully negotiated.  Note: if
+
+
+                               18
+
+John Day                               Data Entry Terminal Option
+June 27,1977                                            NIC 40652
+                                                          RFC 731
+
+
+     the receiver is not in the Waiting  for  Reply  state,  then
+     this is the provider case described next.
+
+     Provider:  When  a  facility  subcommand   is  received,  it
+     should send a facility subcommand with a facility map of the
+     facilities  it provides as soon as possible.  It should then
+     determine what  new  facilities  it  is  providing  for  the
+     Requestor   by  forming  the  logical  intersection  of  the
+     facility map received and the one sent.
+
+     Note:  Although in most cases  the  requestor  will  be  the
+     Server   Host  and  the  provider  will  be  the  User  Host
+     supporting the terminal, this distinction may not always  be
+     true.
+
+T__r_a_n_s_m_i_t_S__u_b_c_o_m_m_a_n_d_s
+
+     There are two kinds of transmit subcommands:  those used  to
+     request  that  data  be  sent  to  the requestor, and one to
+     preface data sent to the requestor.  The  first  kind  allow
+     the requestor to control when, from where and to some degree
+     how  much  data  is  transmitted  from  the terminal.  Their
+     explanation is straightforward and may be found  in  Section
+     2.
+
+     Data may be sent from  the  terminal  as  a  result  of  two
+     events:  the user of the terminal caused the transmission or
+     in  response  to  a  transmit subcommand.  Some programs may
+     wish to know from  where  on  the  screen  the  transmission
+     began.   (This  is  reasonable,  since the terminal user may
+     move the cursor around  considerably  before  transmitting.)
+     Other  programs  may  not  need  such information.  The DATA
+     TRANSMIT subcommand is provided in  case  this  function  is
+     needed.  When used this subcommand prefaces data coming from
+     the  terminal.   The parameters  <x> and <y> give the screen
+     coordinates of the beginning of the transmission.  <x>  must
+     be  less  than or equal to M-1 and  <y> must be less than or
+     equal to N-1.  It is assumed that all data between this DATA
+     TRANSMIT and the  next one starts at the  coordinates  given
+     by  the  first  subcommand   and continues filling each line
+     thereafter according to the constraints of  the  screen  and
+     the  format  effectors  in the data.  Thus an intelligent or
+     sloppy user-host DET implementation (depending on your point
+     of view) need only include a DATA TRANSMIT  subcommand  when
+     the  new  starting  point  is different from the last ending
+     point.
+
+
+6.  Sample Interaction
+
+
+
+                               19
+
+John Day                               Data Entry Terminal Option
+June 27,1977                                            NIC 40652
+                                                          RFC 731
+
+
+The nomenclature of RFC 726 will be used to describe this  example.   To
+quote that RFC:
+
+     "S:"  is sent from serving host to using host.
+     "U:"  is sent from using host to serving host.
+     "T:"  is entered by the terminal user.
+     "P:"  is printed on the terminal.
+
+     Text  surrounded  by  square  brackets([])  is  commentary.    Text
+     surrounded  by angle brackets (<>) is to be taken as a single unit.
+     E.g,  carriage  return  is  <cr>,  and  the  decimal  value  27  is
+     represented <27>.
+
+     We assume that the user  has  established  the  Telnet  connection,
+     logged  on, and an application program has just been started either
+     by the user directly or through a canned start up  procedure.   The
+     presentation on the page is meant to merely group entities together
+     and  does not imply the position of message boundaries.  One should
+     assume that any part of the dialogue may be sent  as  one  or  many
+     messages.   The  first  action  of  the  program  or  Telnet  is to
+     negotiate the DET option:
+
+S: <IAC><DO><DET>
+
+U:  <IAC><WILL><DET>
+
+S:<IAC><DO><OUTPUT PAGE SIZE>           [First negotiate the screen
+                                        size.  In this case we are
+U:<IAC><WILL><NAOP>                     asking the user the size of the
+                                        terminal.  This could have been
+U:<IAC><SB><NAOP><DR><25><IAC><SE>      done before the DET option was
+                                        negotiated.]
+S:<IAC><SB><NAOP><DS><0><IAC><SE>
+
+S:<IAC><DO><OUTPUT LINE WIDTH>
+
+U:<IAC><SB><NAOL><DR><80><IAC><SE>      [Defines the screen to be 25
+                                        lines by 80 characters.
+S:<IAC><SB><NAOL><DS><0><IAC><SE>       The server may use this
+                                        information when formatting
+                                        the screen.]
+S:<IAC><SB><DET><FORMAT FACILITIES>     [Now set the terminal attributes.]
+  <Repeat><Protection, 3 Levels
+  Intensity><IAC><SE>
+
+U:<IAC><SB><DET><FORMAT FACILITIES>
+  <Repeat, Blinking><Protection, 3
+  Levels Intensity><IAC><SE>
+
+S:<IAC><SB><DET><ERASE SCREEN><IAC><SE>     [Erase the screen and
+
+
+                               20
+
+John Day                               Data Entry Terminal Option
+June 27,1977                                            NIC 40652
+                                                          RFC 731
+
+
+                                            start sending the form.]
+  <IAC><SB><DET><FORMAT DATA>
+  <Protection=1, Intensity=1><0>
+  <5><IAC><SE>Name:
+
+  <IAC><SB><DET><MOVE CURSOR><0><1>
+    <IAC><SE>
+
+  <IAC><SB><DET><FORMAT DATA>
+    Protection=1, Intensity=1><0>
+    <8><IAC><SE>
+
+  Address:
+  <IAC><SB><MOVE CURSOR><0><4><IAC>
+    <SE>
+
+  <IAC><SB><DET><FORMAT DATA>
+    Protection=1, Intensity=1><0>
+    <17><IAC><SE>
+  Telephone number:
+
+  <IAC><SB><DET><MOVE CURSOR><32><4>
+  <IAC><SE>
+
+  <IAC><SB><DET><FORMAT DATA>
+    Protection=1, Intensity=1><0>
+    <24><IAC><SE>
+  Social Security Number:
+
+  <IAC><SB><DET><FORMAT DATA>           [Establish a field that doesn't
+    <Protection=1, Intensity=7>         display what is typed into it.]
+    <0><11><IAC><SE>
+
+  <IAC><SB><DET><MOVE CURSOR><32>
+    <5><IAC><SE>
+
+  <IAC><SB><DET><FORMAT FACILITIES>     [Get permission to use Blinking
+    <Blinking><0><IAC><SE>              Attribute.]
+
+U:<IAC><SB><DET><FORMAT FACILITIES>
+    <Repeat, Blinking><Protection,
+    3 Levels Intensity><IAC><SE>
+
+S:<IAC><SB><DET><FORMAT DATA>
+  <Blinking=1, Protection=1,
+  Intensity=1><0><29><IAC><SE>
+
+  Your SSN will not be printed.
+
+  <IAC><SB><DET><HOME><IAC><SE>
+
+
+                               21
+
+John Day                               Data Entry Terminal Option
+June 27,1977                                            NIC 40652
+                                                          RFC 731
+
+
+  <IAC><GA>
+
+The previous exchange has placed a form on the screen that looks like:
+
+Name:
+Address:
+
+
+Telephone Number:                       Social Security Number:
+                                   "Your SSN will not be printed."
+
+where the quoted string is blinking.
+
+The terminal user is  now  free  to  fill  in  the  form  provided.   He
+positions  the  cursor at the beginning of the first field (this usually
+is done by hitting the tab key) and begins typing.  We do not show  this
+interaction  since  it  does  not generate any interaction with the User
+Telnet program or the network.  After the terminal  user  has  completed
+filling in the form, he strikes the transmit key to send the unprotected
+part  of the form, but first the User Telnet program negotiates the Byte
+Macro Option to condense the Field Separator subcommand:
+
+U:<IAC><DO><BM>                         [Negotiate Byte Macro Option.]
+
+S:<IAC><WILL><BM>                       [Define decimal 166 to be the
+                                        Field Separator subcommand
+U:<IAC><SB><BM><DEFINE>                 (see Appendix 3)]
+  <166><6><IAC SB DET FIELD
+  SEPARATOR IAC SE><IAC><SE>
+
+S:<IAC><SB><BM><ACCEPT><166>            [The server accepts the macro.]
+  <IAC><SE>
+
+
+U:<IAC><SB><DET><DATA TRANSMIT><0><6>
+  <IAC><SE>
+  John Doe <166> 1515 Elm St., Urbana, Il 61801
+  <166> 217-333-9999 <166> 123-45-6789 <166>
+
+S:<IAC><SB><DET><ERASE SCREEN><IAC><SE>
+  Thank you.
+
+And so on.
+
+
+
+
+
+
+
+
+
+                               22
+
+John Day                               Data Entry Terminal Option
+June 27,1977                                            NIC 40652
+                                                          RFC 731
+
+
+
+
+
+
+Appendix 1 - Subcommands, opcodes and syntax
+
+
+
+               1    EDIT FACILITIES     <Facilty map>
+               2    ERASE FACILITIES    <Facility map>
+               3    TRANSMIT FACILITIES <Facility map>
+               4    FORMAT FACILITIES    <Facility map 1> <Facility map 2>
+               5    MOVE CURSOR          <x> <y>
+               6    SKIP TO LINE         <y>
+               7    SKIP TO CHAR         <x>
+               8    UP
+               9    DOWN
+               10   LEFT
+               11   RIGHT
+               12   HOME
+               13   LINE INSERT
+               14   LINE DELETE
+               15   CHAR INSERT
+               16   CHAR DELETE
+               17   READ CURSOR
+               18   CURSOR POSITION      <x><y>
+               19   REVERSE TAB
+               20   TRANSMIT SCREEN
+               21   TRANSMIT UNPROTECTED
+               22   TRANSMIT LINE
+               23   TRANSMIT FIELD
+               24   TRANSMIT REST OF SCREEN
+               25   TRANSMIT REST OF LINE
+               26   TRANSMIT REST OF FIELD
+               27   DATA TRANSMIT <x><y>
+               28   ERASE SCREEN
+               29   ERASE LINE
+               30   ERASE FIELD
+               31   ERASE REST OF SCREEN
+               32   ERASE REST OF LINE
+               33   ERASE REST OF FIELD
+               34   ERASE UNPROTECTED
+               35   FORMAT DATA <format map>
+               36   REPEAT     <count><char>
+               37   SUPPRESS PROTECTION <negotiation>
+               38   FIELD SEPARATOR
+               39   FN <code>
+               40   ERROR  <cmd><error code>
+
+
+
+
+                               23
+
+John Day                               Data Entry Terminal Option
+June 27,1977                                            NIC 40652
+                                                          RFC 731
+
+
+
+
+
+
+
+Appendix 2 - Error Codes
+
+
+
+               1    Facility not previously negotiated.
+               2    Illegal subcommand code.
+               3    Cursor Address Out of Bounds.
+               4    Undefined FN value.
+               4    Can't negotiate acceptable line width.
+               5    Can't negotiate acceptable page length.
+               6    Illegal parameter in subcommand.
+               7    Syntax error in parsing subcommand.
+               8    Too many parameters in subcommand.
+               9    Too few parameters in subcommand.
+               10   Undefined parameter value
+               11   Unsupported combination of Format Attributes
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+                               24
+
+John Day                               Data Entry Terminal Option
+June 27,1977                                            NIC 40652
+                                                          RFC 731
+
+
+
+
+
+
+
+
+               Appendix 3 - Use of the Byte Macro Option
+
+
+
+
+     One of the major drawbacks of the DET option is  that  because  the
+     functions  are  encoded  as  Telnet option subnegotiations a fairly
+     high overhead is incurred.  A function like Character Insert  which
+     is encoded as a single byte in most terminals requires six bytes in
+     the DET option.  Originally the only other solution that would have
+     accomplished  the  same  transparency  that  the use of subcommands
+     provides would  have  been  to  define  additional  Telnet  control
+     functions.   However,  since  this would entail modification of the
+     Telnet protocol itself, it was  felt  that  this  was  not  a  wise
+     solution.    Since  then the Telnet Byte Macro Option (RFC 729) has
+     been defined.  This option allows the user and  server  Telnets  to
+     map  an arbitrary character string into a single byte which is then
+     transferred over the net.  Thus the Byte Macro Option provides  the
+     means  for  implementations  to avoid the overhead for heavily used
+     subcommands.  The rest of this appendix suggests how the Byte Macro
+     Option should be applied to the DET option.
+
+     In keeping with the specification of the Byte Macro Option,   macro
+     bytes  will  be  chosen  from  the  range 128 to 239.   For the DET
+     option, it is suggested that macro  bytes be chosen by  adding  the
+     subcommand  code to 128.  In addition, an unofficial DET subcommand
+     might be defined indicating that each side was willing  to  support
+     macro bytes for all subcommands (but not necessarily support all of
+     the  subcommands  themselves)  according  to  this algorithm.  This
+     subcommand would be:
+
+     IAC SB DET DET-MACRO <negotiation> IAC SE
+                                        subcommand code:  254
+
+     where <negotiation> may  have  the  values  of  the  Telnet  option
+     negotiation:
+                    251       WILL
+                    252       WONT
+                    253       DO
+                    254       DONT
+
+     This subcommand is sent by a Telnet implementation to  indicate its
+     willingness to adopt byte macros for all  of  the  DET  subcommands
+     according to the following algorithm:
+
+
+                               25
+
+John Day                               Data Entry Terminal Option
+June 27,1977                                            NIC 40652
+                                                          RFC 731
+
+
+
+        The macro byte for subcommand i will be i+128 and will represent
+        the following string for parameterless subcommands:
+
+        IAC SB DET <subcommand code> IAC SE
+
+        and the following string for subcommands  with  parameters:
+
+        IAC SB DET <subcommand code>
+
+        The default setting for this subcommand is that the  macros  are
+        not in effect, in other words,
+
+             IAC SB DET DET-MACRO WONT IAC SE
+             IAC SB DET DET-MACRO DONT IAC SE
+
+        Negotiation  of  this  subcommand  follows  the  same  rules  as
+        negotiations of the Telnet options.
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+                               26
+
+John Day                               Data Entry Terminal Option
+June 27,1977                                            NIC 40652
+                                                          RFC 731
+
+
+
+
+
+
+
+
+                               References
+
+
+
+     1.  ADM-1 Interactive Display Terminal Operator's Handbook
+           Lear-Siegler, Inc. 7410-31.
+
+     2.  ADM-Interactive Display Terminal Operator's Handbook
+            Lear-Siegler, Inc. EID, 1974.
+
+     3.  Burroughs TD 700/800 Reference Manual, Burroughs Corp., 1973
+
+     4.  Burroughs TD 820 Reference Manual, Burroughs Corp. 1975.
+
+     5.  CC-40  Communications Station:  General Information Manual.
+           Computer Communication, Inc.  Pub. No. MI-1100. 1974.
+
+     6.  Crocker, David.  "Telnet Byte Macro Option," RFC 729, 1977.
+
+     7.  Data Entry Virtual Terminal Protocol for Euronet, DRAFT, 1977.
+
+     8.  Day, John.  "A Minor Pitfall in the Telnet Protocol,"
+           RFC 728, 1977.
+
+     9.  Hazeltine 2000 Desk Top Display Operating Instructions.
+           Hazeltine IB-1866A, 1870.
+
+     10.  How to Use the Consul 980:  A Terminal Operator's Guide
+           and Interface Manual.  Applied Digital Data Systems, Inc.
+            98-3000.
+
+     11.  How to Use the Consul 520:  A Terminal Operator's Guide
+           and Interface Manual.  Applied Digital Data Systems, Inc.
+           52-3000.
+
+     12.  Honeywell 7700 Series Visual Information Projection (VIP)
+            Systems:  Preliminary Edition. 1973.
+
+     13.  An Introduction to the IBM 3270 Information Display System.
+            IBM GA27-2739-4. 1973.
+
+     14.  Naffah, N.  "Protocole Appareil Virtuel type Ecran"
+            Reseau Cyclades.  TER 536. 1976.
+
+
+
+                               27
+
+John Day                               Data Entry Terminal Option
+June 27,1977                                            NIC 40652
+                                                          RFC 731
+
+
+     15.  Postel, Jon and Crocker, David.  "Remote Controlled
+            Transmission and Echoing Telnet Option", RFC 726
+            NIC 39237, Mar. 1977.
+
+     16.  Schicker, Peter.  "Virtual Terminal Protocol (Proposal 2).
+            INWG Protocol Note #32., 1976.
+
+     17.  UNISCOPE Display Terminal :  Programmer Reference .  Sperry-
+            Univac UP-7807 Rev. 2, 1975.
+
+     18.  Universal Terminal System 400:  System Description.  Sperry-
+            Univac UP-8357, 1976.
+
+     19.  Walden, David C. "Telnet Output Line Width Option."
+            NIC # 20196, 1973, also in ARPANET Protocol Handbook, 1976.
+
+     20.  Walden, David C.  "Telnet Output Page Size"  NIC # 20197,
+            1973, also in ARPANET Protocol Handbook, 1976.
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+                               28
+
\ No newline at end of file