Is there a reference guide for the phoneme representations used by Repeat After Me?

Question

Repeat After Me uses a distinct phoneme representation (shared with the command-line tool "say"). For example, the word "repeat" maps to "_rIXp1IYt." There is a small appendix of certain vowels and consonants provided here:

http://developer.apple.com/library/mac/#documentation/UserExperience/Conceptual/SpeechSynthesisProgrammingGuide/Phonemes/Phonemes.html#//apple_ref/doc/uid/TP40004365-CH9-SW1

but it only covers a very small subset of the representable sounds. Is there a reference to the phoneme representation?