Thanks.

Let me restate to make sure I understand correctly:

While the native operating systems of both the AS/400 and HP 3000 are proprietary.  The older and more robust version of the POSIX layer for the HP 3000 makes it open; even though both systems are POSIXly compliant.

Have I got it?

>>> "Joe Geiser" <[log in to unmask]> 08/25/99 09:02AM >>>
<snip>

What makes the HP3000 "open" - is introduction of POSIX to MPE, which permits
MPE/iX to run code compiled using POSIX libraries (which resemble or could even
be the same as Unix libraries).
<snip>
The AS/400 also has a POSIX layer, but it is not nearly as robust as MPE/iX as
IBM was a little late in the game to introduce POSIX to OS/400.  Yes, they
<snip>