Section 3.4.5 of the structures spec currently reads

"For each attribute use in the {attribute uses} whose {required} is false and whose {value constraint} is not ·absent· ..."

Consider a global attribute declaration:

  <attribute name="a" default="xyz"/>

And a reference to this global declaration:

  <attribute ref="a"/>

In this case, the attribute declaration has a default value, but the reference (hence the attribute use) doesn't. Strictly following 3.4.5, "xyz" is *not* applied when "a" is missing in the instance. Intended?

Shouldn't 3.4.5 refer to the "effective value constraint" as opposed to "whose {value constraint}"?