This document describes updated methods for handling Unicode strings representing usernames and passwords. The previous approach was known as SASLprep (RFC 4013) and was based on Stringprep (RFC 3454). The methods specified in this document provide a more sustainable approach to the handling of internationalized usernames and passwords. The PRECIS framework, RFC YYYY, obsoletes RFC 3454, and this document obsoletes RFC 4013. [[ NOTE TO RFC EDITOR: please replace "YYYY" in the previous paragraph with the RFC number assigned to draft-ietf-precis- framework. ]]