Your editor routines must conform to the same general programming conventions as the nonstandard label processing routines discussed under Processing Nonstandard Labels, for size, design, register usage, entry points, and work areas. As discussed under Nonstandard Labels, you must use the EXCP macro instruction to perform needed input/output operations.

If your editor routines have more than one load module, names for the additional modules must begin with the prefix OMODVOL for the open routine, or EMODVOL for the EOV routine.

DFSMSrmm makes use of the OMODVOL1 and EMODVOL1 routines. DFSMSrmm changes the flow of control so that DFSMSrmm code is entered before OMODVOL1 and EMODVOL1 are entered.

With tape cartridges, the open and EOV routines normally use EXCP appendages when processing labels. For the duration of the open or EOV, they normally save labels in virtual storage buffers to improve performance by avoiding an unnecessary change of direction on the tape. The EXCP appendages simulate most types of channel programs that read. For channel programs that they do not simulate, they move the tape to the point where your routine expects the tape to be and then allow the channel program to run. This simulation improves performance.

If your routine does I/O, it should use the DCB that is in the work area. Do not substitute or modify the DEB appendage vector table.