/ James Clark <> was heard to say:
| It's common to have a collection of common optional attributes:
|
| <define name="common.atts">
| <optional>
| <attribute name="id">
| <data type="xsd:ID"/>
| </attribute>
| </optional>
| ...
| </define>
|
| Sometimes, you want one of the common atts that is normally optional to
| be required on one particular element. With TREX at the moment, you can
| simply do this:
|
| <element name="def">
| <ref name="common.atts"/>
| <attribute name="id">
| <data type="xsd:ID"/>
| </attribute>
| ...
| </element>
|
| If the rule was that a pattern must not permit duplicate attributes,
| then the above approach would not be possible.
I don't think that's a great hardship. The ID case is just about the only
example of this case (where you have a collection of common atts but one
is sometimes required) and it's fairly easy to work around.
<define name="common.atts">...</define>
<define name="common.atts.idreq">...</define>
And then <ref> the one you want. You could even factor out the "core"
common attributes, if you wanted.
I think allowing multiple attributes is potentially confusing for
users, and not hard to work around, so I'm inclined to forbid it.
Be seeing you,
norm
--
| The human race consists of the
XML Standards Engineer | dangerously insane and such as are
Technology Development Group | not.--Mark Twain
Sun Microsystems, Inc. |
