Telnet Data Entry Terminal option
RFC 732

Document Type RFC - Unknown (September 1977; No errata)
Updated by RFC 1043
Obsoletes RFC 731
Last updated 2013-03-02
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NWG/RFC# 732                                  DAY 13-Sep-77 18:38  41762
Data Entry Terminal Option

Network Working Group                                           John Day
Request for Comments: 732                                               
NIC: 41762                                             12 September 1977

Obsoletes: 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.

  The Network Virtual Data Entry Terminal (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.

John Day                                                        [page 1]


NWG/RFC# 732                                  DAY 13-Sep-77 18:38  41762
Data Entry Terminal Option

    (Although most DET's will support one or more peripheral devices
    such as a paper tape reader or a printer, this option does not
    consider their support. Support of peripheral devices should be
    treated by a is 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.

  Facility Functions  (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 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

John Day                                                        [page 2]


NWG/RFC# 732                                  DAY 13-Sep-77 18:38  41762
Data Entry Terminal Option

    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
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