The problem with the above is that |...| is not valid lexical syntax in R6RS. You can encode an identifier like |tag:srfi.schemers.org,2000:146:fxmapping| in R6RS but it looks ugly.
In addition, you can mint a version 5 UUID from either an https: or a tag: URI using url-namespace-uuid (6ba7b811-9dad-11d1-80b4-00c04fd430c8) as the foundation. In one of my projects I mint a per-user tree of version 5 UUIDs, where the root is computed from the user's email address using (make-relative-uuid (make-relative-uuid dns-namespace-uuid email-host-name) email-local-part), and all child UUIDs using (make-relative-uuid parent-uuid description-string).