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In generating a g-file for compilation, it is useful to record the date and time of creation, the version retrieved, the module's name, and so on in the g-file itself. This information appears in a load module when one is eventually created. SCCS provides a convenient mechanism for doing this automatically. Identification (ID) keywords appearing anywhere in the g-file are replaced by appropriate values according to the definitions of those ID keywords. The format of an ID keyword is an uppercase letter enclosed by percent signs (%). For example,
%I%is the ID keyword replaced by the SID of the retrieved version of a file. Similarly, %H% and %M% are the date and name of the g-file, respectively. Thus, executing get on an SCCS file that contains the PL/I declaration
DCL ID CHAR(100) VAR INIT('%M% %I% %H%');
gives (for example) the following:
DCL ID CHAR(100) VAR INIT('MODNAME 2.3 07/18/85');
When no ID keywords are substituted by get,
the following message is issued:
No id keywords (cm7)
This message is normally treated as a warning by get although the presence of the i flag in the SCCS file causes it to be treated as an error. For a complete list of the keywords provided, see get(1).