I think TPT should make conductors (i.e. METL, PSCN, NSCN, TTAN, etc...) able to be made indestructible by setting the life to >0. That would make it easier for the coders because they don't have to code another element. I don't think life has any use right now anyway.
One problem I can see is that SPRK would have to have some way of keeping that value when 're - placing' the conductor, possibly through tmp2.
--EDIT:
And BTRY
No life is not used in metals for countdown it's used in SPRK. (I think)
But if you set the life > 0 the metal can't conduct
When metals get SPRK'd it sets its type to SPRK and its ctype to the metals type and its life to 4. each frame it decreases the life by 1 until it reaches 0. At this point it sets its type back to the metals and sets the metals life to 4. It then decreases its life by 1 until it reaches 0 at which point it can get SPRK'd again.
As I said, what about tmp2?