Nonstandard labels do not conform to IBM or ISO/ANSI standard label formats. You can design them and provide routines to write and process them. There are no requirements regarding their length, format, contents, and number, except that the first record on a BCD, EBCDIC, or ASCII tape cannot be a standard volume label.

Figure 1 shows some examples of how you can organize tape volumes with nonstandard labels. Other variations are possible. Because your routines do the positioning, there are no special requirements for multivolume or multiple data set organizations. Your routines write all labels and tapemarks. If an operating system access method is used to retrieve the data, tapemarks should precede and follow the data set to indicate the end-of-data-set condition for forward and backward read operations.

Nonstandard labeled tapes are not supported in a library (either by the Tape Library Dataserver or by a manual library).

Figure 1. Examples of Tape Organizations with Nonstandard Labels

• No Tapemarks: This type of organization can be created by your nonstandard label processing routines, and read with the EXCP technique or BSAM. Do not use with QSAM because there is no tapemark to signal end-of-data.
• Tapemarks Delimiting the Data Set: This is the recommended organization. The tapemarks are written by your nonstandard label processing routine. When the tape is read by an operating system access method, the tapemark following the data set signals end-of-data for forward read operations, and the tapemark preceding the data set signals end-of-data for backward read operations.
• Tapemarks Delimiting the Labels and the Data Set: This is an expansion of the preceding organization. The operating system does not handle the additional tapemarks that precede and follow the labels. Instead, your nonstandard label processing routine writes and uses them.