3.1.5.12 Password Change and Set

[RFC3244] describes the message flow for the Windows extension to the password change mechanism which enables setting passwords. [RFC3244] section 2 shows that targname and targrealm are optional fields, but does not describe when they should be set. If the fields are present, then this is a request to set a password and the initial flag is not required. If the fields are absent, then this is a password change.