Job Entry Subsystem 1

Job Entry Subsystem 1 (JES1) was released by IBM to provide for VS1 the basic functions that users of VS1's predecessor, MFT, had when using HASP.

IBM proclaimed JES1 to be "the single most important addition" to the job scheduling provided by VS1. IBM Systems Journal defined JES1's services as Spooling and scheduling, adding "Its three major components are peripheral services, central services, and queue management."

Reaction? "Users hated it.". Why? HASP and ASP users often had made local modifications (edits), and wanted to retain their investment.

JES1 permitted batch jobs to be submitted from remote sites, executed on an IBM mainframe, then produce printed output either at the originating site or, if desired, at the main site or another remote site.

The JOB Card JCL was given a new option: TYPRUN=SCAN, whereby a job could be submitted for quick feedback, and - if no errors were detected - be submitted again (without TYPRUN=SCAN on the JOB Card.

...
Wikipedia