Prompted by a question on c.t.t., I've done a sweep over all of TeX Live
and added all of the expl3 prefixes which are in use to the database I
mentioned some time ago. As this has been done in a somewhat automated
manner, package authors are advised to check the results
I'd also like to strongly encourage developers to register their
prefixes by submitting them either directly to the team, to me or to
sending them to the list. I'll try to pick up new uses as they pop up on
the CTAN list, but may not catch everything.