In section 8.4, after listing the to-specs:
“The restrictions listed in 8.2.4 Default use of XPath 1.0 for Expression Languages MUST apply to XPath used as a query language.”

Query language is only used in the Variable Variant of the to-spec, but applying the restrictions of section 8.2.4 on the query would remove the context node, thus making the variable and part attributes irrelevant.

It makes more sense to enforce the restrictions of section 8.2.4 on expressions in the Expression Variant of the to-spec. Should the text have been "... MUST apply to XPath used as the expression language.” ?

Thanks.