how is a plane is defined?

I am thinking of creating a stand alone add in for solidworks. However, I am surious if the way I would write my code is possible.

How is a plane in solidworks defined? I know mathmatically you need 3 points to define a plane. Is there any way to extract 3 points from any plane of your choice in solidworks?

Thanks for all the help!

If this is something that I can find out for myself from documentation, just point me in the direction.

Cheers!

SolidworksApi macros