Fw: Namespaces

[John Cowan]

Oren Ben-Kiki wrote:

> Why wasn't the DTD spec extended to handle global attributes (regardless of
> namespace issues) instead of sneaking them in the namespace spec? Global
> attributes make the same amount of sense for non-prefixed attributes within
> a single XML language. This is the root of the problems here - _what is the
> benefit gained from placing this in the namespace spec_? Is there one? Is it
> worth it? Can we revoke it?

I think that some of your problems come from misunderstanding the
term "global attribute": unfortunately, the examples in REC-xml-names
don't help.

A "global attribute" is *not* an attribute that can be placed on
every element in a document, or at least it need not be.  A global
attribute is simply one which has by intention the same meaning
in all elements in which it appears.  To reuse my earlier example,
given an appropriate binding for the "iso4217" prefix, one might
have a global attribute "iso4217:currency" which applies to only the
PRICE element in a supply catalog.  The "iso4217" prefix signals
the application that it can use a *global* understanding of
currency --- namely, that the value of this attribute is an ISO 4217
currency code (USD, GBP, EUR, etc.).

The example of html:class is unfortunately "global" in both the
intended sense (its meaning is independent of the element on which
it appears) and the unintended sense (it may appear on any element).
So it is a bad example for explaining global attributes.

>From a DTD viewpoint, global attributes are just ordinary attributes,
valid only where an ATTLIST declaration allows them.

-- 
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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