I have a device that requires a 220v 20amp outlet. The male plug on
this is like:

- |
o

I have a 220v 40amp recepticle on the wall which is like:

u
| o |
_
|

On the plug I assume the two prongs are both hots and the round prong
is the saftey ground with no neutral on the plug.

On my recepticle are the two straight slots the hots, the u the saftey
ground and the upside down L the neutral?

I can't remove this outlet and my concern is to not mix up the ground
and the neutral.

I'm not going to replace the outlet. I just want to make a little
extension cord adapter.