For some candid and amusing thoughts on the standards process check out the chapter "The Politics of Open Systems" in The Open Book by Marshall T. Rose, Prentice Hall, Englewood Cliffs, NJ 1990.
See Brian K. Reid, "Scribe: A Document Specification Language and its Compiler," Ph.D. Dissertation, CarnegieMellon University, Pittsburgh, PA, Oct. 1980.
For an excellant overview of UNIX document processing tools, see "The Unix System Document Preparation Tools: A Retrospective, " by Brian Kernighan, in the AT&T Technical Journal, Vol. 68, No. 4, July/Aug. 1989.
A 5-volume series of books on computers and typesetting published by AddisonWesley, Reading, MA, all authored by Donald Knuth, represents some of the finest computer software documentation ever produced. They are (A) The TEXbook, (B) TEX: The Program, (C) The METAFONT Book, (D) METAFONT: The Program, and (E) Computer Modern Typefaces.
A good introduction to PostScript Level 2 is presented in "Moving Up to Level 2 " by Bruce Fraser, in Publish, Nov. 1991, Better yet, check the Web for the PostScript FAQ archived at http://www.cis.ohio-state.edu/hypertext/faq/usenet/postscript-faq.
Absolutely everything you ever wanted to know (and more) about SGML is in The SGML Handbook by Charles Goldfarb, edited and with a forward by Yuri Rubinsky, Oxford University Press, New York, 1990. Not only is the information clear, through, and readable, but this book serves as a model for the presentation of an ISO standards.
The classic survey of hypertext systems is J. Conklin's "Hypertext: An introduction and survey," IEEE Computer 20,9, Sept. 1987. It may be a little dated, but is still quite valuable; the Web didn't spring up out of a vacuum.
For a thorough description of HyTime see "Making Hypermedia Work: A User's Guide to HyTime" by Steve J. DeRose and David G. Durand, Kluwer Academic Publishers, 1994.