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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

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 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   ]

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