Screen Resolutions

I know I must be missing something very obvious here, but I can't find the answer in any
help files or on the forum. I'm transitioning from OS-9 to OS-X (using the MATLAB Intel
Beta on a new MacBook Pro).

In OS-9 there used to be the following Screen function:

Screen(0,'Resolutions')

I would use this to get a list of all possible screen resolutions for the available monitor(s)
and then I'd use the following command to implement a resolution switch to something
appropriate and 'safe':

Screen(0,'Resolution',res)

What would the equivalent commands be in PTB-3?

I'm aware of [w,h]=Screen('WindowSize',0) which will get the current size
and hz=Screen('NominalFrameRate',0) which will set the refresh rate; but how does one
get a list of possible resolutions and specify a one of them in PTB-3?

Thanks,
Adam