Is there any documentation on the message format being sent to port 523
(DAS) and the returned replies?

We've got a problem with a tool that says that the DAS is not
responding, while the IBM tools says that the DAS is alive and well.

Obviously, the tool is at fault.... but we need to confirm this as the
tool can find some of the DAS ssytems.

Very curious but we're trying to chase down exactly what is causing the
problem.