I'd say no on this one. Reasons:
- if we leave it out now we can add it later; the reverse is not true
- one of my goals for SAX is to present to people who want to see XML
as "just elements and attributes". I happen to think this is a
reasonable way to want to look at XML; present entities as an
*authoring* convenience; from the point of view of the downstream
parser, your handy local XML parser makes the issue go away
- I'm far from convinced that external entities will actually get
that much use.
-Tim