ID constraints for the Resource Data module

Hi Ryan, David, all,

While checking that the modules are following the same ID-related constraints as the extensions, I've found that it's not the case
for the Resource Data module.

The constraint for the id for <resourceItemRef>:

"The value of the OPTIONAL id attribute MUST be unique among all <resourceItemRef> children of the enclosing element."

The constraint for the id for <resourceItem>:

"The value of the OPTIONAL id attribute MUST be unique among all <resourceItem> children of the enclosing element."

Both <resouceItem> and <resourceItemRef> can exist inside a single <resourceData> element.
And <resourceData> can exist zero, one or more times within <file> and <unit>.

So to work properly with the URI Fragment identification we need both ids to have the following constraint:

The value of the id attribute MUST be unique among all <resourceItemRef> and <resourceItem> elements of the immediate enclosing
<file> or <unit> element.

Would that be OK?


As a general question also: why allowing several <resourceData> per <file> or <unit>? That element has no attribute, so technically
it makes no difference to have all <resourceItem>/<resourceItemref> is one or more <resourceData>.

Any thoughts?
-yves