What is the domain of strerror()?

[Doug Gwyn]

In article <1249 at microsoft.UUCP> w-colinp at microsoft.uucp (Colin Plumb) writes:
>It says that strerror() maps the error number passed to it to an error
>string, but I can't find any description of what a valid error number is.

That's easy; anything the standard says is an error number is allowed,
and anything else is up to the implementation.  I.e. the non-zero value
of errno, as set by some functions according to the standard, is an
acceptable "error number" for strerror().  Presumably any other non-zero
value that the implementation assigns to arrno is also acceptable to
strerror().

The Rationale refers you to perror(), 4.9.10.4, where this connection
is clearer.