I looked and I couldn't really find much, but I did notice these 2:
Bomb with a tmp of 2 and life of 0 doesn't blow anything up (used to be in wiki)
!set tmp bubw 1 - the carbonated water explodes into CO₂

In my mod a lot more elements use tmp and tmp2 for extra customization, but I think only FILT does in this because then people that don't use PROP or the console wouldn't know secret customizations.