[xml] attribute//ref in RelaxNG

[Sebastian Rahtz <sebastian rahtz computing-services oxford ac uk>]

Testing the 2.5.4 release of xmllint with my
RelaxNG schemas, I get a lot of errors about

  Found forbidden pattern attribute//ref

which I can isolate to this test case

XML:

<a b="c"/>

RNG:

<start>
  <ref name="a"/>
 </start>         

<define name="a">
  <element name="a">
   <text/>
   <attribute name="b">
    <ref name="c"/>
   </attribute>
  </element>
 </define>

<define name="c">
  <text/>
</define>

The RelaxNG validators by James Clark and Sun both
say this is fine, and I cannot off-hand see anything in the
Relax spec which would forbid it.

Is this a bug in libxml2, or am I not reading the
spec closely enough?

-- 
Sebastian Rahtz      OUCS Information Manager
13 Banbury Road, Oxford OX2 6NN. Phone +44 1865 283431