RasMol commands are documented in the RasMol Manual. They are also documented in RasMol's built-in help, although at present (10/96) the built-in help omits some of the more recently added commands (such as stereo). At present, the web version of the Manual is more up to date (to RasMol version 2.6 beta-2).
Chime uses a superset of RasMol commands. Documentation on the commands unique to Chime may be found at MDL's site or in the Draft Chime-Command Manual.
See the Guide to Script Creation for RasMol and Chime for a detailed manual on writing scripts, and the Tutorial for Scripting Chime and RasMol by MDLI's Mitch Miller.