Input Formats for CREF Jul75

This document, dated July 1975 from Digital Equipment Corporation, specifies the input formats for CREF, a cross-reference facility. It details two primary input formats:

1. Early Input Format (Section 2.0): Used by older versions of assemblers (like MACRO prior to V30, PALX, and F prior to V06). This format uses specific ASCII codes (33-37) to indicate code types (op codes, macro names, normal symbols) and the end of a line or program break. It is explicitly stated that this format should not be used for new program development.

2. Current Input Format (Section 3.0): Produced by newer versions of assemblers and compilers (like MACRO V30+, F40 V06+, ALGOL V06+, and FORTRAN-10 V04+). This format relies on an extensive set of control characters for various functions:

   • Beginning and Ending Control Characters (Section 3.1): RUBOUT characters (B, C, F, A, D, E) define the start and end of CREF data on a line, control line number incrementing, and mark program breaks.
   • Symbol-Definition Control Characters (Section 3.2): CONTROL-A through CONTROL-O define symbols, instruction types (op codes, macros), mark symbol block beginnings/ends, and handle symbol manipulation.
   • Character-Count-Definition Control Characters (Section 3.3): CONTROL-A through CONTROL-F (and others, up to 100(8) for 64 characters) specify the number of characters in a symbol or instruction.

The document provides a detailed listing of each control character, its ASCII code, and its specific meaning to CREF, including a code example to illustrate the current input format.