As far as I know this is an undocumented feature. I have referred to it in the past, it was tucked away in my "5 Uses for Utility Plug-ins" post last year but in the context of the quick tips series I think its so useful it deserves a post all to itself.
To consolidate a selection, I'm sure most of us are aware of Option+Shift+3 (Alt+Shift+3 on the PC) which will render a new file or files across the timeline selection. What far fewer people know is that by adding Ctrl (Start on the PC) Pro tools will render a -20dB, 1KHz sine wave across the edit selection. Endlessly useful for those times when you need some audio to check an output or diagnose a routing or gain problem. I had always assumed that this command followed the default as set up in the Audiosuite Signal Generator plug-in but when checking my facts for this post I discovered that setting a user default has no effect on this shortcut.
If you have ever found yourself instantiating a plug-in like signal generator or Boom! just to run some audio for test purposes then you should try this - A shortcut which saves you time (well, it's called a shortcut for a reason...)