[SunRescue] GDM20E20 what is this little button?

[Paul Phillips]

I've got a Sun GDM20E20 monitor.

On the very left end of the controls at the bottom of the monitor is a
small recessed button that is about 1/4 inch square.  Under it are three
dots.

It would have to be depressed with a pen or pencil.

If someone has this monitor -- What does this button do?

Also, the next button over seems to have three functions, but I don't know
what they are.  

Thanks for any information.

Paul Phillips
paul at partitura.com