Insert block - Switch between basepoint and 0,0,0

I'm inserting blocks into my drawing and the block has a basepoint and a 0,0,0 point. The CAD guy who usually works with me is off today but he has a keyboard method of switching between the 2 points when inserting the block.

Its a fairly straight forward thing on his keyboard, nothing he has set up but standard in autocad.

I've had a try hitting a few keyboard buttons this morning but can't seem to do it.

Anyone know how to tab between insertion points?

Press the control key prior to selecting the insertion point. I know that works with dynamic blocks anyway....