RFC 7564, "PRECIS Framework: Preparation, Enforcement, and Comparison of Internationalized Strings in Application Protocols", May 2015
Note: This RFC has been obsoleted by RFC 8264Source of RFC: precis (app)
Errata ID: 4568
Reported By: Sam Whited
Date Reported: 2015-12-20
Section 3 says:
Preparation entails only ensuring that the characters in an individual string are allowed by the underlying PRECIS string class.
It should say:
Preparation entails applying some or none of the rules specified for a particular string class or profile thereof to an individual string, and ensuring that characters in the resulting string are allowed by the underlying PRECIS string class.
The original text makes it sound like preparation is ONLY validating that the characters in a string are allowed in the underlying PRECIS string class, however, some profiles (for example, see the UsernameCaseMapped profile) specify that some of the rules must be applied first (in the case of UsernameCaseMapped, preparation includes first applying the Width rule).