PREFIX  jext:    <java:arq.examples.ext.>

SELECT DISTINCT ?x 
{
    [] ?p [] .
    ?p jext:localname ?x .  # Sets ?x

    ## And these ...
    ?p jext:localname ?x .  # Checks ?x
    # Checks again - different way
    { ?p jext:localname "p" } UNION { ?p jext:localname "label" } . 
}