VMS Help SCA, SCA Topics, Callable Routines, SCA$QUERY_FIND, Argument  *Conan The Librarian (sorry for the slow response - running on an old VAX)

 query_context
    type:       $SCA_QUERY_CONTEXT
    access:     read/write
    mechanism:  by reference

    An SCA query context that describes a query expression to be
    evaluated.