This decompresses to a Disk Copy image which contains the bootable Network Server
Diagnostic Utility tool. You can either image it directly to a 1.44MB HFS formatted 3.5" floppy,
or copy the file diags to such a floppy (see the accompanying Read Me). Make sure the ANS is
shut down, turn the key to the service (left) position, insert the disk and power up the server.
It should automatically enter diagnostics.

NSDU has at least one known bug: more than 256MB of RAM may cause it to hang up during testing.
You should remove RAM above this amount before doing the complete system or memory test,
or test in groups.