Appendix A contains outtakes from the text of the novel -- places where explanations got technical enough to bog down the story and had to be trimmed back.

 http://www.sff.net/people/wmccarth/apdxa.htm

Appendix B contains a glossary.

 http://www.sff.net/people/wmccarth/apdxb.htm

Appendix C is a partial compilation of my more coherent notes from the development phase.

 http://www.sff.net/people/wmccarth/apdxc.htm

There is an Appendix D as well, but it has to do with character issues rather than technical ones.  It also contains plot spoilers, so is not included here.