This topic documents Intended Programming Interface and Associated Guidance Information.

An external writer allows an installation to perform output processing for data sets not eligible for processing by the primary job entry subsystem (JES2 or JES3). For example, an external writer processes data sets going to printers, plotters, diskettes or data sets that are to be stored on a device not supported by JES.

There are two major parts of the IBM-supplied external writer that can be modified or replaced by an installation: the output writing routine and the output separator routine.

See z/OS MVS Using the Functional Subsystem Interface for information in subsystem interface (SSI) function code 1 on how to write your own external writer.