If you try to read a RIB archive that is actually empty, Aqsis produces a syntax error:
09/20/2009 10:41:06 ERROR: syntax error at empty.rib line 1
09/20/2009 10:41:06 ERROR: Unrecognised RIB request at empty.rib line 1
The easiest way to reproduce this is just to create an empty file and try to render it which also shows the above error.
What I would have expected is that reading an empty file has no effect at all.
This is aqsis 1.4.2 (OSX).
PS: I have a deja-vu feeling filing this bug report, but I didn't see the issue mentioned among the bug reports, so I'm adding it now. My apologies if it's a duplicate.