			CBACK VERSION 2.46 INFORMATION

	Cback works as a filter program, reading the output of cfront, and
producing cleaned up C code.  The C code is modified according to a rule
file, which controls which modifications to make.

USAGE
	cback2.46 [-d] [-e] [-i input] [-o output] [-q[q]] -r rules

DESCRIPTION
	The -i option specifies a file to read instead of standard input.

	The -o option specifies a file to write instead of standard output.

	The -q option stops the output of the copyright message.

	The -qq option stops the output of the copyright message and the
version identification.

	The -r option specifies the file of rules which controls cback.

	The -d options causes cback to call its destructors and clean up
its internal memory before exiting, which can take a significant amount of
time and has no effect on the output of cback.

	The -e option is the opposite of the -d option.  The -e option is
on by default, unless the -d option is used.

	The -d option and the -e option should not be used by the user, and
are only described for completeness.

EXAMPLES
	cfront +L <file.cc | sun4/cback2.46 -e -q -r sun4/cback.rc2.46 >file.c
		Apply appropriate rules for a sun4.

	cfront +L <file.cc | sun4/cback2.46 -e -q -r /dev/null >file.c
		Format output, don't apply any rules.

RULES FILE
	The rule control file is an ascii file consisting of one rule per
line.  Blank lines and lines beginning with a '#' are ignored.  A rule is a
string of characters, which often is a symbolic representation of what the
rule accomplishes.

	Each rule begins with a keyword, followed by a ':' if the rule is
turned on, or a '!' if the rule is turned off.  Rules can appear more than
once.  The last occurence with its ':' or '!' controls whether the rule is
on or off.

	An exception to this is the size rules, which cannot have a '!' after
them since a size is not a binary value which can be turned off.  If these
need to be ignored then use the comment '#' character at the beginning of
the line.


ERROR HANDLING
	The supplied script file "sun4/cback.sh2.46" will output the result
of cback if cback returns a zero exit code, otherwise it will output
the original output of cfront.  Thus if 'cback' has an internal assertion
error of some sort it will exit with a non-zero exit code, and the code
output by "sun4/cback.sh2.46" will be as if 'cback' was never called.

	Cback attempts to detect that all operators have valid types.
If it detects an invalid combination it will produce an error message,
and turn off all of its rules.  However, it will still output valid c
code.

BUGS
	cback has been known to complain about "line too long" when it
reads its input from a pipe.

LIMITATIONS
	cback was designed to process the output of cfront.  Certain
constructs in the C language (that cfront does not output) will not be
processed.  cback has been tested with the output of cfront versions 1.2,
2.0 and 2.1 and 3.x.
