[Tzdist] How should tzdist support rscale?

(Cc'ing both tzdist and calsify because the issue is about the interaction
of specs defined by the two groups...please trim to one or the other if the
topic ends up being unique to that group.)

A question recently occured to me about the interaction of rscale and tzdist.

Should it be possible for a VTIMEZONE -- either inline in an iCalendar
document, or distributed by tzdist -- to use an RSCALE?

There are some natural use cases for this -- Iran uses the Persian calendar
to set its DST observances, and Israel used the Hebrew calendar from
2005-2012.  Right now the IANA tzdata just expands non-Gregorian rules to a
list of dates, but in principle, RSCALE would be a much more natural (and
compact) way of representing rules like these.

However, tzdist has no way to negotiate the use of iCalendar extensions.
Should one be defined?

For that matter, the rscale draft doesn't talk about its use in VTIMEZONE
at all (indeed, it asserts that VTIMEZONEs are always specified in Gregorian
time).  Should it?

-- 
Jonathan Lennox
[e-mail]