I note the IETF last call was issued for rev. 2. That revision no longer exists, hence I reviewed rev. 3. This document specification of a "User Principal Name", I believe, is inadequate. The I-D indicates that a user_principal_name is a sequence of 0 to 65535 bytes in the form of user@domain. However, such a form implies the value is a character string, but there is no mention of what character set/encoding is used here. I would think interoperability requires both client and server to have a common understand of what character set/encoding is to be used. Additionally, there is no discussion of UPN matching. Are byte sequences that differ only due to use of different Unicode normalizations to be consider the same or differ? Are values case sensitive or not? etc.. The domain_name field suffers not only from the above problem, but is flawed due to use of the outdated "preferred name syntax" of RFC 1034. This syntax doesn't allow domains such as 123.example. The text should likely reference the RFC 1123 which updates the "preferred name syntax" for naming hosts. Additionally, no mention of how International domain names (IDNs) are to be handled. I recommend ABNF be used to detail the syntax of each of these fields and that the I-D detail how values of these fields are to be compared. Additionally, the I-D should discuss how IDNs are to be handled. -- Kurt _______________________________________________ Ietf@xxxxxxxx https://www1.ietf.org/mailman/listinfo/ietf