X Window System Protocol, version 11: Alpha update April 1987
RFC 1013

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Network Working Group                                Robert W. Scheifler
Request for Comments: 1013                                     June 1987

                  X WINDOW SYSTEM PROTOCOL, VERSION 11
                                 Alpha Update
                                  April 1987
     Copyright (c) 1986, 1987 Massachusetts Institute of Technology
                   X Window System is a trademark of M.I.T.

Status of this Memo

   This RFC is distributed to the Internet community for information
   only.  It does not establish an Internet standard.  The X window
   system has been widely reviewed and tested.  The internet community
   is encouraged to experiment with it.  Distribution of this memo is
   unlimited (see copyright notice on page 2).

M.I.T.                                                          [Page 1]
RFC 1013                                                       June 1987

   Permission to use, copy, modify, and distribute this document for any
   purpose and without fee is hereby granted, provided that the above
   copyright notice appear in all copies and that both that copyright
   notice and this permission notice are retained, and that the name of
   M.I.T. not be used in advertising or publicity pertaining to this
   document without specific, written prior permission.  M.I.T. makes no
   representations about the suitability of this document or the
   protocol defined in this document for any purpose.  It is provided
   "as is" without express or implied warranty.

    Author: Robert W. Scheifler
           Laboratory for Computer Science
           545 Technology Square, Room 418
           Cambridge, MA 02139

    Contributors:
           Dave Carver (Digital HPW)
           Branko Gerovac (Digital HPW)
           Jim Gettys (MIT/Project Athena, Digital)
           Phil Karlton (Digital WSL)
           Scott McGregor (Digital SSG)
           Ram Rao (Digital UEG)
           David Rosenthal (Sun)
           Dave Winchell (Digital UEG)

    Implementors of initial server who provided useful input:
           Susan Angebranndt (Digital)
           Raymond Drewry (Digital)
           Todd Newman (Digital)

    Invited reviewers who provided useful input:
           Andrew Cherenson (Berkeley)
           Burns Fisher (Digital)
           Dan Garfinkel (HP)
           Leo Hourvitz (Next)
           Brock Krizan (HP)
           David Laidlaw (Stellar)
           Dave Mellinger (Interleaf)
           Ron Newman (MIT)
           John Ousterhout (Berkeley)
           Andrew Palay (ITC CMU)
           Ralph Swick (MIT)
           Craig Taylor (Sun)
           Jeffery Vroom (Stellar)

   This document does not attempt to provide the rationale or pragmatics
   required to fully understand the protocol or to place it in
   perspective within a  complete system.  Knowledge of X Version 10
   will certainly aid in understanding this document.

M.I.T.                                                          [Page 2]
RFC 1013                                                       June 1987

   The protocol contains many management mechanisms that are not
   intended for normal applications.  Not all mechanisms are needed to
   build a particular user interface.  It is important to keep in mind
   that the protocol is intended to provide mechanism, not policy.

   This document does not attempt to define precise formats or bit
   encodings.

   -------------------------------------------------------------------

M.I.T.                                                          [Page 3]
RFC 1013                                                       June 1987

   SECTION 1.  TERMINOLOGY

   Access control list
           X maintains a list of hosts from which client programs may be
           run.  By default, only programs on the local host may use the
           display, plus any hosts specified in an initial list read by
           the server.  This "access control list" can be changed by
           clients on the local host.  Some server implementations may
           also implement other authorization mechanisms.

   Active grab
           A grab is "active" when the pointer or keyboard is actually
           owned by the single grabbing client.

   Ancestors
           If W is an inferior of A, then A is an "ancestor" of W.

   Atom
           An "atom" is a unique id corresponding to a string name.
           Atoms are used to identify properties, types, and selections.

   Backing store
           When a server maintains the contents of a window, the
           off-screen saved pixels are known as a "backing store".

   Bit gravity
           When a window is resized, the contents of the window are
           not necessarily discarded.  It is possible to request the
           server (though no guarantees are made) to relocate the
           previous contents to some region of the window.  This