7.4.1 File Limitations

All of the standard rules of COBOL apply in multi-record mode, with the following limitations:

Only files that require no record locking can be opened in multi-record mode. This limitation is enforced silently on both the client and the server. If a user tries to open a file that requires record locking in this mode, the file is still opened, but not in multi-record mode. In other words, multi-record mode does not affect the lock mode specified by the COBOL program, but the lock mode may affect whether records are sent in single or multi-record packets.

Files open in this mode may not be read backward. (i.e., READ-NEXT commands are supported. READ-PREVIOUS commands are not.) The purpose of this mode is to improve sequential performance. If you attempt to read a file backward that has been opened in multi-record mode, an error 9B results (requested operation is not supported).