> Only no known details if the only document you're reading is the notoriously poorly-specified RFC
To be fair, in RFC9562 I did cite two documents that are UUID Version 2 specifications. But RFC4122 was too cryptic for my taste.
As for the historical UUID types specified by the 0-7 Variant space:
We are starting work on an informational RFC that will help folks understand those.
See https://github.com/yocto/draft-yocto-uuid if you want to add to some discussions and/or review text. We are still a bit early into the stages but I hope to have some progress soon.
Though I am working on a way to solve this problem with UUIDs beyond 128 bits so we don't have to truncate the hash.