D McGilvray wrote:
> Hi there, I've been searching in vain for an example of exactly *how* 
> notations are to be used beyond simply declaring external entities.

They're intended as a way of attaching additional non-XML information to 
an XML document.  Their use is application-specific... but in fact I 
have never seen an application use them and I can't think of a really 
good use case for them. They seem to be one of the features which was 
inherited from SGML because some specific user wanted them, and which 
everyone else has been assiduously ignoring ever since.

Tim Bray's summary, from the Annotated XML Spec 
(http://www.xml.com/axml/testaxml.htm):

"A notation is a name and an external identifier; the idea is that it's 
supposed to be helpful in figuring out how to deal with the data to 
which it's attached. The suggestion that the XML processor itself might 
do something with the notation is really bogus; that's not its job. So 
if anyone is interested, it would have to be the application, not the 
XML processor. Furthermore, the application might be able to handle the 
data itself without any help, once it knows the notation."

By the way, I ***HIGHLY*** recommend that anyone who is working with XML 
take the time to browse through the Annotated XML Spec. It's based on 
XML 1.0 (Tim hasn't had the time to update it for 1.1), but it's still 
the single best explanation I've seen of how and why all the design 
decisions in XML were made and what the legalisms really mean. Even if 
you think you know XML well, you'll probably learn a lot; I'm still 
discovering details.


-- 
Joe Kesselman / Beware the fury of a patient man. -- John Dryden