Good grief Rainbow, do you write dice rollers for a living? I feel like a dog trying to read a wizard's spellbook. I'm gonna have to play around with that to even understand what's going on :)
Edit - Ahhhhh, ok. So I was completely unaware that the keep/drop system went by each dice expression. I thought it only split by "+" or "," ... silly me!
If anyone else thought the same as I did, to put it really, really simply:
[[ { 1d1 * 12 *(1-1d1) }k1 ]]
I had thought the braces contained a single sub-roll, as far as the keep/drop operation is concerned. But it's two rolls, obviously.
Keeping one roll drops the second 1d1 and it's treated as a 0 in further calculations, and the result is 1 * 12 * 1, which is 12.
Keeping two rolls includes the second 1d1, so the parentheses becomes 0, and 1 * 12 * 0 is 0.
Rainbow did explain all of this perfectly well, I was just unaware that step 1 was possible, so the rest of the post confused me greatly!