Before OPEN or EOV goes to the label editor routine it calls the label anomaly exit. The exit's return code causes one of these actions:
If the exit returns with all the anomaly bits off and it is an output tape, then the system changes the tape to try to override the problem.
If the problem is that volume label information is needed to write the label, then the exit must supply the complete label in EBCDIC in the area that TEPMLABEL points to and set bit TEPMNEWLAB in the main parameter list. The caller will do any necessary conversion to ASCII. If the exit sets TEMPMNEWLAB on but it is not a valid volume label, then the system will write a message and not call the exit until IPL.
If the exit supplies the label or authorizes destruction of labels, the exit takes responsibility for security and expiration date processing.
If any anomaly bit remains on, then the system will call the label editor (OMODVOL1 or EMODVOL1) if the condition is one that the label editor is designed to handle. If the condition is one that the label editor is not designed to handle, then the result will be as stated in the description.
If the job requests a specific volume and bit TEPAABEND is also set, the system abends the job.
Note that return code 0 for this exit is not supported.
If neither the exit nor the label editor rejects the volume, then the system can call the exit more than once for the same volume, but for a different reason.