Entities in XSchema
cowan at locke.ccil.org
Tue Jun 9 17:33:25 BST 1998
Many, many XML-DEVers wrote, in effect:
> Entities in XSchemas suck big ones.
I surrender. Even when the XSchema-processors-can't-expand-entities
meme has worked its way out of the system, there remains the
Why-would-you-want-to-do-that???? meme, and I very well realize there's
no end to that argument. "Eleven men well armed", as Jno. Swift
has it, "will certainly subdue one single man in his shirt."
If, however, purely declarative information is to be removed from
XSchemas, then I think that parts of the attribute-type and
attribute-value declaration syntax should go. In particular,
attribute types are reduced to Name (ID, IDREF, ENTITY, NOTATION),
Names (IDREFS, ENTITIES, NOTATIONS), Nmtoken, Nmtokens, and CData;
attribute values are reduced to #REQUIRED, #FIXED "foo", and other.
Without information on the names of valid entities and notations,
and potentially without information on IDs, then ID, IDREF,
ENTITY and NOTATION are indistinguishable; IDREFS, ENTITIES, and
NOTATIONS also all look the same. The only remaining distinction
Saying what the specific default value is or whether there is none
is overspecific (the DTD must bear this information, and
an XSchema would be either redundant or conflicting, a Bad Thing);
the only three cases are: a) the value must be present and must
be "foo" (#FIXED), b) the value must be present but can be anything
(#REQUIRED), or c) the value need not be present.
John Cowan http://www.ccil.org/~cowan cowan at ccil.org
You tollerday donsk? N. You tolkatiff scowegian? Nn.
You spigotty anglease? Nnn. You phonio saxo? Nnnn.
Clear all so! 'Tis a Jute.... (Finnegans Wake 16.5)
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