+/** \brief converts CQL sortby to sortkeys ..
+ \param cn CQL tree
+ \param out result buffer
+ \param max size of buffer (allocated)
+ \retval 0 OK
+ \retval -1 ERROR
+*/
+YAZ_EXPORT
+int cql_sortby_to_sortkeys_buf(struct cql_node *cn, char *out, int max);
+