These were contributed by people from Xerox and also from Medley and earlier customers, for distribution with sources and an implicit license for creation of derivative works; this is in the days before "Open Source" was a thing.
Some of these are included in full.sysout; some migrated between library and lispusers over time.
In order to tidy the lispusers directory, some files have been moved:
Previous enumerations of released "lispusers" packages and instructions have (temporarily) been moved to docs/lispusers.
Some files have been moved to obsolete/lispusers.