In case the 100 picture thing you're mentioning also corresponds with the ID and not just pictures themselves, then you'll have to go a little bit higher (108 should be the highest ID used for a picture).
I mean the recall you had a list once showing which commands you had implemented and not, and as long as I recall correctly and little has happened in the meantime, Get Event ID, and Get Terrain ID should be missing.
Btw. how many recursive event calls does your engine handle?