Slashes in variable names in generated algebra?

[Rob Vesse]

Andy

Just got a question from one of our devs about algebra ARQ is generating.  The 
original query is sq-08.rq from the subquery tests of the 1.1 test suite, the 
following is the fragment of the algebra he was asking about:

(extend ((?max ?/.0))
          (group () ((?/.0 (max ?/y)))
            (quadpattern (quad <urn:x-arq:DefaultGraphNode> ?/x 
<http://www.example.org/schema#p> ?/y)

Under what circumstances will ARQ insert slashes into variable names?

Thanks,

Rob