Without a prefix, this almost
invariably refers to BSD Unix release 4.2. Note that it is an
indication of cluelessness to say "version 4.2", and "release
4.2" is rare; the number stands on its own, or is used in the more
explicit forms 4.2BSD or (less commonly) BSD 4.2. Similar remarks
apply to "4.3", "4.4" and to earlier, less-widespread releases
4.1 and 2.9.
