Creates a query expression that matches a specific entity.
    Format
      SCA$QUERY_SELECT_OCCURRENCE  query_context,
                                   entity_handle
1 – Arguments
 query_context
    type:       $SCA_QUERY_CONTEXT
    access:     read/write
    mechanism:  by reference
    An SCA query context that is to describe a specific entity.
 entity_handle
    type:       $SCA_HANDLE
    access:     read/write
    mechanism:  by reference
    An SCA entity handle that describes the entity that the newly
    defined query context is to match.
2 – Condition Value Returned
    SCA$_NORMAL           A query expression has been successfully
                          defined.
3 – Description
    The SCA$QUERY_SELECT_OCCURRENCE routine creates a query expression
    that matches a specific entity.
    You use this routine to specify queries based on the results
    of previous queries. The entity_handle parameter is obtained by
    traversing the results of a previous query evaluation.
    Typically, the query context of the entity_handle parameter is
    not the same as the query_context parameter. However, they can be
    the same. If they are the same query context, then that previous
    query is replaced with the query defined by this routine and, as a
    result, entity_handle becomes invalid.
    This routine will become obsolete in a future version of SCA. The
    SCA$SELECT_OCCURRENCE routine supersedes this routine.