RFC 178 (rfc178) - Page 1 of 11

Network graphic attention handling

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Network Working Group                                      Ira W. Cotton
Request for Comments: 178                                          MITRE
NIC: 7118                                                  June 27, 1971


                   NETWORK GRAPHIC ATTENTION HANDLING


1.0 INTRODUCTION

   Discussions of network graphic protocols have thus far primarily
   dealt with protocols for the description of graphic data to be
   displayed.  RFC 86 proposed a Network Standard Graphic Data Stream
   (NGDS) which would serve to convey graphic images expressed in the
   Network Standard Display List (NGDL).  RFC 94 expanded on this
   proposal, and pointed out some shortcomings of the original scheme.
   RFC 125 also replied to RFC 86 with comments and extensions, but also
   recognized that a protocol for graphic display alone is insufficient
   to support an interactive graphic system.

1.1 TOPICS COVERED

   The present paper addresses itself to this requirement.  The process
   of attention handling is briefly described, various graphic
   configurations are discussed, input devices are surveyed to identify
   the types of data which they produce, and an attention protocol is
   suggested.

1.2 VIEWPOINT

   It should be made clear at the onset that the discussion which follow
   will be from the viewpoint of a graphics user or a graphic
   application program serving one or more users.  Our concern is with
   third-level protocols only.  We assume the network is capable of
   delivering arbitrary bit streams from terminal to graphic application
   program, but don't care how this is accomplished.

2.0 ATTENTION-HANDLING

   In order to demonstrate the need for an attention protocol, we must
   first define what is meant by "attention" and "attention-handling."
   We therefore begin by borrowing the definitions given in a recent
   survey of this area(1).








Cotton
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