About draft-freed-sieve-in-xml-00

I like your I-D about Sieve in XML and find it is a good idea.

I have two remarks (not very important).

First, why did you choose the W3C Schema language instead of RelaxNG?
I understand it may be a matter of taste, but I'm curious.

Second, to represent Sieve comments, you use XML comments. But a
conforming XML parser MAY ignore comments so there is a risk that
round-trip conversion may lose comments. Moreover, your schema (and
the associated XSL script) forbids to put comments intended for the XML
version only such as:

<!-- Produced by sieve2xml on 2007-11-02. Do not edit. -->

Such comments would be translated back to Sieve, which would be
unfortunate.

I suggest instead to create an element <sieve-comments> to store them.