RE: Notations

Michael Kay (M.H.Kay@eng.icl.co.uk)
Tue, 8 Dec 1998 09:41:00 -0000


> Correct, so why do you want:
>
> ><!ELEMENT OrderTime (#PCDATA) NDATA Iso8601_DateTime >
>
> when you can just have
>
> <!ELEMENT OrderTime (#PCDATA)>
> <!ATTLIST OrderTime
> notation NOTATION (Iso8601_DateTime) #FIXED "Iso8601_DateTime">
>
One minor problem, as I pointed out not so long ago, is that the latter
declaration can be overridden in the internal DTD subset. So FIXED doesn't
really mean FIXED at all.

The real reason though is probably psychological. Us database folks have
been so firmly educated to distinguish types from instances that we find it
unnatural to implement an attribute of a type as if it were an immutable
attribute of each instance. I can learn to live with it though!

Mike Kay