IMP Core Environment Standard


                    Section 13: Reserved Identifiers
       *** WILL BE SHIFTED OUT OF STANDARD AS OF NEXT EDITION ***

   In the fullness of time, this section will be removed from the "Core"
standard to become a document in its own right.  Its purpose is to
identify common "useful" procedures to implementers in terms of a
definition and an identifier, so that if an implementer chooses to add
such a facility to an implementation it will normally have the same
identifier as on other implementations.  This allows programmers to
avoid any "false friend" effect when coding outside the bounds of the
Core standard proper.  An example of a possible problem area might be in
moving from a system in which a WAIT procedure was available with
parameter integer Millisecs to one where WAIT was defined to have
parameter long real Seconds.

   Procedures defined in this section of the standard must never be
predefined.  Instead, they must be introduced into the program by means
of an implementation defined include or spec statement.  An
implementation is free to implement these same functions with other
identifiers, but must not implement these identifiers with alternate
definitions.