I actually considered inventing a new three-character one for "USBC" (maybe "SNC" for "SBC+NOP"?), but thought it would be better to not to add to the existing confusion regarding the names of these undocumented instructions. (Some of them have a long history, not all of them are perfectly chosen, but they are what they are.) The same applies to "ANC" and "ANC2": is the distinction of these externally similar instructions really worth ruining the simplicity and beauty of the three-letter convention?