The following are a set of non-overlapping categorization of all labels of characters from [\-A-Za-z09], with examples. It is an elaboration of the distinctions made in defs.
Names for various subgroupings are also useful. For example, Terms 1-5 are all "putative A-Labels" or "ACE Prefix" labels. Terms 4-6 could be called "Broken IDN". Terms 2-6 could be called "Invalid IDN".
Thus for each of 1-4 there is a corresponding Unicode String (Label):
Note that apparent Punycode strings might not map to Unicode, such as the "a" in "xn--a".
Inconsistency in current