trang: translating comments between compact and xml

Hi,

trang translates

element 
( a # case a
| b # case b
)
{ empty }

into

<?xml version="1.0" encoding="UTF-8"?>
<element xmlns="http://relaxng.org/ns/structure/1.0">
  <choice>
    <name>a</name>
    <!-- case a -->
    <name>b</name>
  </choice>
  <!-- case b -->
  <empty/>
</element>

moving the second comment past the end of the name class.  I realize that translation
of comments is not normative;  however, since the comments are translated by trang,
is there a list of patterns where comments do not stay in place during translation?

David Tolpin
http://davidashen.net/