in diagnostic_procedures.html is mentioned :- IBM manual N/C 360 APT Application Description (H20-0181-1) http://www.archivist.info/apt/aptos/apt360/doc/manual/diagnostic_procedures.html This page has useful mentions of error numbers and where they come from I think it needs making machine readable (sql) I have done that to the vocabulary in AXTABL.ASM I have put them in ClassId order note INSERT is there twice sql is select * from axtabl order by classId,subClass,proTapClass,proTapSubClass,id result is http://www.archivist.info/apt/aptos/apt360/orig_source/apt/php/vocab.php Dave Caroline