AD evaluation comments: draft-ietf-sieve-variables

Just a small nit and a question:

The Abstract should be more clear about the focus of the document.  It
describes "This extension", but it doesn't explain what's being extended.

RFC 2234 has been obsoleted.  Can the reference to 2234 be updated to refer
to 2234bis instead?

These are minor.  Please hold off on making any changes until IETF last call
comments can be addressed.

-Scott-