This directory contains files used to build the C cross reference program
cxref.  This is the Bell Sys 5.2 cxref.

In this directory you will find the following source files:

	cxr.c  This file contains the code for the main driver for
	       cxref; it also contains the backend processing code.  It
	       is compiled to generate 'cxref'.  This is the Bell
	       'cxr.c' file, plus 'owner.h' has been merged inline.  So
	       'cxref' is a single-file command.

	cxlocal.c  A file needed to build the special compiler frontend,
		   xpass, used by cxref.  This contains the code from
		   S5.2 cxref/xlocal.c, and also "customized" code
		   needed to satisfy external references for a compiler
		   front-end, etc.  Along the lines of S5.2
		   cxref/lint.c.

	xpass_rel.c  An sccs-version control file for the xpass files
		     maintained in the cxref directory (cxlocal.c,
		     cxmacdefs).  It should be deltaed when any of the
		     files (cxlocal.c, cxmacdefs) are modified.

	makefile  make command file to build cxref, xpass, xcpp.  The
		  install/release200 target can be used to recursively
		  reinvoke the makefile with the correct macros for a
		  S200 build.

Cxref operates by invoking a specially made version of cpp (xcpp), and
ccom (xpass).  These are built from the cpp source and ccom source
(front-end files) which have been modified to contain cxref support
code.  When the cpp and ccom files are compiled with -DCXREF they
generate special versions which run to produce cross-reference
information (rather than code) from a source file.

Rather than keeping separate copies of the cpp and ccom source (making
bug fix tracking unpredictable), the code to support CXREF was directly
merged into the cpp and ccom source files (ala Sys 5.2 approach).

The build command file makefile copies the files it will need from the
system source directories for cpp and ccom in order to build xcpp and
xpass.  Note that the file cxlocal.c is also used in forming xpass.  It
contains cxref-type functions, and "stubs" needed to complete a
front-end only version of the compiler.

The version of xpass seen via 'what' is defined by two id numbers:  the
xpass_rel.c id, and the id for the compiler:  ccom/Uni_rel.c.
