This glossary covers a mixture of standard technical retro-terminology, specific conventions, etc. with the following objectives: it can replace a FAQ, it explains all these weird stipulations and it can be used en guise de tutorial.
I'll be happy to extend it with your suggestions (and help): You can contribute!.
A. Retro Glossary
1. Special Rules and Conventions
B. Fairy and Heterodox Glossary
C. FIDE Laws of Chess
D. Codex for Chess Composition
Note: This is by far not a complete glossary of fairy and heterodox chess, but all stuff mentioned elsewhere on the Retro Corner should be there.
The requirement for legality of a position may depend on the rules of chess valid at composition time of the problem. For example, the stalemate rules changed over time.
This codex deals with general principles of chess composition activities such as composition, solving and publication. The codex is [...] intended to offer constructive guidance in areas where there has been no central guidance before. It is not intended to be a body of established law which problemists must observe on pain of being condemned of heresy or worse. [...]