Unknown key shares in MMUSIC

After completely failing to remember and take into account feedback
during the avtcore meeting last time (thanks for the reminder
Jonathan), I would like to draw the attention of this group to this
draft:

https://datatracker.ietf.org/doc/draft-thomson-avtcore-sdp-uks/

The latest version builds on the a=dtls-id work in this group.
However, Jonathan's reminder highlighted a critical shortcoming of
that: it only works for DTLS.  We still have uses of TLS-over-TCP that
would not be addressed by the current iteration of the draft (though
they would have for the previous version).

One relatively simple solution is to define dtls-id as tls-id instead,
but that's disruptive.

I'd like to discuss this issue with an eye to resolving it before or
at Chicago; I realize that there is a probably a tight agenda, but the
outcome of that discussion might affect a very-far-advanced
draft-ietf-mmusic-dtls-sdp-21.