Jonathan called to ask what the word for two of a set of triplets is called. I'm thinking twerps would work.
Over at Volokh there was a discussion about Romanettes. Apparently that's the word for the lowercase Roman numerals in statutes and contracts. (iii) would be Romanette 3. It is used frequently in transactions and contracts. You can see why it would be a useful word to have when speaking, but would seldom need to be written.