1ndex and 0ffset. I like it.
I love what you did here. Great mnemonic!
ooo, I'm going to steal that; clever.
> (which everyone outside of CS does)
In set theory (math foundations), ordinals also start at 0.
That usage gets awkward though when you want to talk about the offset from one array index to another (and the array is 0-based). In actual (common) usage, the distinction between index and offset is the distinction between absolute and relative positions.
This is an aside, but I think that "index" is the wrong name. I wish that "index" meant you start counting at 1 (which everyone outside of CS does) and "offset" was the name for starting at 0.