RFC336

NIC 9929 Ira Cotton NWG/RFC #336 Mitre Level 0 Graphic Input Protocol 5 May 1972

    Level 0 Graphic Input Protocol

       At its meeting on April 16-18 the network Graphics working
       group began to consider the definition of levels of protocol
       for graphic Input Protocol.  The following describes the
       Level 0 graphics input protocol.

       The philosophy guiding the establishment of this protocol is
       the same as suggested in RFC #178, "Network Graphic Attention
       Handling." Briefly, all input will be described by type,
       origin, and length, followed by the actual data.

       Only two types of input are defined at Level 0: text and
       simple position.

          Text Input

              Text input will be conveyed in the following format:

               TEXTIN : DEVICE : COUNT: Text String

             TEXTIN is a protocol code indicating the nature of this
             input string.  For the present this code is defined to
             be 1.

             DEVICE is a code indicating the device from which the
             input originated.  The following codes are presently
             defined:

                  0 - unspecified device
                  1 - primary keyboard
                  2 - tablet
                  3 - mouse
                  4 - joystick
                  5 - lightpen
                  6 - cursor
                  7 - keyset
                  8 - mouse & keyset

NIC 9929 NWG/RFC# 336 Level 0 Graphic Input Protocol

             Count is an integer number indicating the number of
             characters (bytes) which follow.

             Text String is a string of "Count" bytes of characters
             in network ASCII.

          Position Input

               Simple position data will be conveyed in the
          following format:

               POSIT : DEVICE : COUNT : x : y

             POSIT is a protocol code indicating that this string
             contains position data.  For the present this code is
             defined to be 2.

             DEVICE is a code indicating the input device on which
             this data was generated.  The codes are as defined
             above.

             COUNT is an integer number indicating the number of
             bytes of data which follow.  This includes data for
             both x and y coordinates.  Thus, the number of bytes of
             x coordinate data is COUNT divided by 2.  At level 0,
             COUNT should always be 4, since at this level all
             coordinates are expressed in 2 bytes of data.

             x and y coordinate data are represented as signed
             fractions in the same fashion that position data is
             represented in the Level 0 graphic output protocol.

       It should be emphasized that input data from a level 0
       graphics user which is not in a format described above should
       be sent on a different link than the graphics input link.
       This may be desirable for certain applications to avoid the
       overhead of the protocol.

   [ This RFC was put into machine readable form for entry ]
   [ into the online RFC archives by BBN Corp. under the   ]
   [ direction of Alex McKenzie.                   12/96   ]