JES2 initializes the setup characteristics of a device based on the specifications supplied on a device (printer/punch) statement. JES2 groups a job's output data sets into output groups (job output elements) based on the data sets' output requirements. The user defines these requirements in the job's JCL or by JES2-supplied defaults.

When JES2 selects work for a device to process, JES2 compares the device's characteristics to the output requirements associated with the output groups waiting for processing. If JES2 finds an output group that matches the device's characteristics, JES2 routes the data sets associated with that output group to that output device.

If JES2 can not match an output group with a device, selection of the output group does not occur. The output group remains on the spool until the operator uses a $T command to change an output device specification to match that output group. Alternatively, the operator can use the $T O command to change the data set's characteristics to allow the device to select the output group. If an output device selects an output group for processing, but certain setup characteristics do not match exactly, JES2 issues the $HASP190 message notifying the operator of the characteristics that require changing.