My results so far follow.  I've listed them by OS though there is also
a dependency on libc.

AIX 4.3:     errno = 0 after strerror(-1) returned "Error -1 occurred."
Cygwin B20:  errno = 0 after strerror(-1) returned "error -1"
IRIX 6.5:    errno = 0 after strerror(-1) returned NULL
Redhat 6.2:  errno = 0 after strerror(-1) returned "Unknown error 4294967295"
Solaris 2.6: errno = 0 after strerror(-1) returned NULL
Solaris 7:   errno = 0 after strerror(-1) returned NULL


What I'd like to know is whether any version of strerror() returns a
non-NULL pointer that does not contain a print of the number.
-- 
Pete Forman                 -./\.- Disclaimer: This post is originated
Western Geophysical           -./\.-  by myself and does not represent
pete.forman@westgeo.com         -./\.-  the opinion of Baker Hughes or
http://www.crosswinds.net/~petef  -./\.-  its divisions.