[ih] What is the origin of the root account?

[Lyndon Nerenberg]

The documentation's use of "super user" rather than "root" isn't surprising.  The kernel's concept of "super user" was tied to having an (effective) uid of 0.  The kernel had no knowledge of a password file, let alone a convention of having a uid=0 account named root.

The original UNIX manpages were not only accurate and concise, they were pedantically correct to a fault.  It's a model and style of documentation writing that, sadly, vanished by the early 1990s.

--lyndon