Enforcement entails applying all of the rules specified for a
particular string class or profile thereof to an individual
string, for the purpose of determining if the string can be used
in a given protocol slot.
The "OpaqueString Profile" specified in "Preparation, Enforcement, and Comparison of Internationalized Strings
Representing Usernames and Passwords", RFC 7613.
The "UsernameCaseMapped Profile" specified in "Preparation, Enforcement, and Comparison of Internationalized Strings
Representing Usernames and Passwords", RFC 7613.
The "UsernameCasePreserved Profile" specified in "Preparation, Enforcement, and Comparison of Internationalized Strings
Representing Usernames and Passwords", RFC 7613.