Input Formats for CREF

This document describes the two input formats supported by CREF, a utility used for cross-referencing symbols in source code.

• Early Input Format: Used by older versions of MACRO, PALX, and F40. It uses ASCII codes (33-37) to denote instruction types, macro names, end-of-line markers, normal symbols, and program breaks. This format is discouraged for new development.
• Current Input Format: Used by modern versions of MACRO, FORTRAN, and other assemblers. It utilizes specific control characters (RUBOUT B/C/F/A/D/E) for beginning and ending data streams, and various CONTROL-A through CONTROL-O characters to define symbols, instruction types, macros, and character counts.

The manual provides technical definitions and examples of the current format to ensure compatibility with modern listing outputs.