This function invokes the CCL parser. It converts a given CCL FIND query to an RPN query which may be passed to the yaz_search() function to perform a search. To define a set of valid CCL fields call yaz_ccl_conf() prior to this function. If the supplied query was successfully converted to RPN, this function returns TRUE, and the index rpn of the supplied array result holds a valid RPN query. If the query could not be converted (because of invalid syntax, unknown field, etc.) this function returns FALSE and three indexes are set in the resulting array to indicate the cause of failure: errorcodeCCL error code (integer), errorstringCCL error string, and errorposapproximate position in query of failure (integer is character position).