[TUHS] History of m6?

Hi. Doug McIlroy is probably the best person to answer this. Looking at the V3 and V4 manuals, there is a reference to the m6 macro processor. The man page thereof refers to A. D. Hall, The M6 Macroprocessor, Bell Telephone Laboratories, 1969 1. Is this memo available, even in hardcopy that could be scanned? 2. What's the history of m6, was it written in assembler? C? 3. When and why was it replaced with m4 (written by DMR IIRC)? More generally, what's the history of m6 prior to Unix? IIRC, the macro processor in Software Tools was inspired by m4, and in particular its immediate evaluation of its arguments during definition. I guess I'll also ask, how widespread was the use of macro processors in high level languages? They were big for assembler, and PL/1 had a macro language, but I don't know of any other contemporary languages that had them. Were the general purpose macro processors used a lot? E.g. with Fortran or Cobol or ... I'm just curious. :-) Thanks, Arnold