While supporting the Jaguar OpenVMS systems I was involved in various projects programming in DCL (Digital Command Language).
Many of the programs were specific to the housekeeping of the OpenVMS systems, such as backup & restore, startup & shutdown, printer and batch queue maintenance, user maintenance etc.
Downtime of the Jaguar systems was valued at £250,000 per hour, so it was essential that all system software was reliable, well tested and documented.
Stringent change control procedures were in use to control the implementation any system changes. However since I was also providing the operating system support, I was effectively wholly responsible for many of these projects.