Bug 2955. Workaround for lack of atomic operations in GCCE standard libraries (fall back to default use of Mutex)
<?xml version="1.0"?>
<!-- Attribute uniqueness: different attributes with same local name -->
<foo xmlns:a="http://example.org/~wilbur"
xmlns:b="http://example.org/~kipper">
<bar a:attr="1" b:attr="2"/>
</foo>