tsrm_ls

I'm trying to grok PHP Source, and I suspect I've missed some "Beginner" guide somewhere. I'm looking at the TSRM*_* data types in the header files, and have backtracked as far as 'tsrm_ls' and then... I'm not finding a place where that is defined. I've grepped php-src for it, and only see it used, not defined. I also grepped /usr/include and /usr/local/include, thinking maybe it's a standard OS thing. I know TSRM is thread-safe-resource-manager, but the LS_DC LS_CC etc system isn't getting into my brain... L for Long? S for string? What am I missing? TIA! (Hoping to do something useful someday...) -- Like Music? http://l-i-e.com/artists.htm