Notations

[Charles Reitzel]

Rick Jelliffe wrote:
| Joel Bender wrote:
|>There are really two problems: (1) what pattern of character strings 
|>are acceptable for content (attribute value or element content) and 
|>(2) how should those patterns be mapped to atomic types?
|>...Both the 'type' of value and the 'encoding' of the value must be
|>specified.
|
|Which assumes that there are "atomic types" independent of domains.

I think of data types as domains, too.  E.g. non-negative integers vs.
positive integers, temperature in degrees Farenheit, etc., etc.  It seems
that everyone has different notions of what constitute the "atomic" types.
I also agree with the many folks who have said that the XML spec should not
be burdened with the large set of atomic types that would be required to
make everybody happy.  Which may be why NOTATIONS were invented in the first
place.  It is probably one of those compromises that makes no one truly
happy but let's everyone get their (wildy divergent) work done with the same
spec.  No small feat indeed.  Although "attribute Notations" will solve some
real problems (XPointers to compound keys!), I can do useful work with
element values today.

Like Joel says, it seems the only physical issue for XML is how to translate
the logical structure to and from a character stream.  The physical
structure any given application uses at run-time is application, system and
programming language dependent.  Thus the NOTATION need only denote the
logical structure, allowing the application to direct the character data to
its preferred translation code, e.g. a regexp engine.  XML is off the hook!

I'd guess this is why the PUBLIC id is required while the SYSTEM id is
optional for NOTATIONs.  The path to the handler probably belongs in a
system dependent application config file, not the DTD.  Much like how web
servers use config files to look up MIME handlers.  

Regards,
Charles Reitzel
creitzel at mediaone.net


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