Since the publication of RFC 4122 in 2005, a number of additional versions of universally unique IDs (UUIDs) have been proposed. A number of errata have also been verified against the original specification, motivating a full revision of the UUID specification with the additional versions added. This working group will produce a standard-track RFC4122bis specification based on limited review of RFC4122 that will include resolution of verified or held errata and incorporation of the following additional UUID versions, using draft-peabody-dispatch-new-uuid-format as a guide: - Field-compatible version of UUIDv1 optimized for improved database locality - Time-ordered UUID based on Unix epoch timestamp - UUID version for vendor-specific use cases Other aspects of UUIDs, such as alternative representations and UUIDs that are other than 128 bits in length, will also be considered and the working group may produce specifications on those topics. They will not be considered, however, prior to completion of RFC4122bis, and such milestones will be negotiated with the responsible AD prior to work commencing.