I have found Chapter 5, MM Macros, of the Eroff Desktop Typesetting System (Palo Alto, CA: Elan Computer Group, Inc., 1988) to be an excellent reference for the MM macros. Yes, some of the internals of groff's MM have changed, but still very useful, absent anything better.
It contains 111 pages, with sections: A Introduction pp. 1-2 B Usage 3-6 C Formatting Concepts 6-10 D Paragraphs and Headings 11-21 E Lists 21-32 F Memorandum and Released-Paper Documents 33-47 G Business Letters 47-52 H Displays 53-60 I Footnotes 60-64 J Page Headers and Footers 65-71 K Table of Contents and Cover Sheet 72-74 L References 75-76 M Miscellaneous Feature 76-84 N Errors and Debugging 85 O Extending and Modifying MM Macros 86-88 P Summary 89 Q MM and Formatting Error Messages 90-94 R MM Macros Name Summary 95-97 S MM String Name Summary 98 T MM Number Register Summary 99-100 U INDEX 101-111 I see that Eroff is still available: http://www.elancomputergroup.com/eroff.asp and that its documentation (including, I'd guess, the MM Macros documentation) can be bought for $75. "Eroff is a complete professional typesetting system, ideal for publishing manuals, proposals, research papers and other medium to large size documents. Élan has combined increased functionality and many enhanced features with the standard UNIX markup language, troff, to provide a system that is a complete professional publishing package. ... Enhancements to Troff o Image Inclusion - Merge graphics directly with text in one document. Accepted formats: MacPaint, PCX PostScript, Raw Bitmap & TIFF o Color and Grayscale support for any text and graphics. o Filling/Shading - New graphics primitives to fill and shade objects with either grayscale or a variety of patterns. o Kerning - Sectored Contour Kerning adjusts inter-character spacing for a very professional look. o Laser Printer Drivers - Included: PostScript, such as Apple LaserWriter, and PCL, such as the HP LaserJet family and compatibles. o Landscape & Portrait Printing - All components of EROFF can be printed in landscape or portrait formats! o Font Management - Intelligent font management provides fewer redundancies in downloading of fonts for quicker printing. o N-up Printing - Print 2-up (two logical pages side-by-side in landscape mode), 3-up, and 4-up. Ideal for creating manuals or reference charts. o Native Language Support - Supports your local language with 8-bit keyboards. o Code Insertion - You may insert your own commands to pass through to the printer. o Internal Output Redirection - One may use the > and >> options to .tm, .pm, and the .pt command to send/append output to a file . o Comprehensive Documentation - Comes complete with over extensive documentation." Robert Marks -- http://www.agsm.edu.au/bobm
