Unfortunately while the above is legal in XPath 2.0 in an expression, it's
still not allowed in a pattern - the syntax of patterns is much more
restrictive.

Okay, thanks.  I was sure that I had used syntax like that at some
point while working with XSL.  I've never been aware of the
restrictions placed on patterns.

If you've got a schema then you might find that the elements you want to
match are all members of the same substitution group, in which case you can
write comments//schema-element(inline) where "inline" is the head of the
substitution group. Or the elements might all have the same type, in which
case you can write comments//element(*, inlineType).

Thanks for the suggestion.  Unfortunately, right now I'm working
without a schema, so I can't use this immediately.  I will try to keep
this in mind for the future, though.