Query objects represents queries.
     ZOOM_query ZOOM_query_create(void);
     void ZOOM_query_destroy(ZOOM_query q);
     int ZOOM_query_prefix(ZOOM_query q, const char *str);
     int ZOOM_query_cql(ZOOM_query s, const char *str);
     int ZOOM_query_sortby(ZOOM_query q, const char *criteria);
   
    Create query objects using ZOOM_query_create
    and destroy them by calling ZOOM_query_destroy.
    RPN-queries can be specified in PQF
    notation by using the
    function ZOOM_query_prefix.
    The ZOOM_query_cql specifies a CQL
    query to be sent to the server/target.
    More query types will be added in future versions of YAZ, such as
    CCL to RPN-mapping, native CCL query,
    etc. In addition to a search, a sort criteria may be set. Function
    ZOOM_query_sortby specifies a 
    sort criteria using the same string notation for sort as offered by
    the YAZ client.