Elmo wrote:
....

Because yours answers one of my questions, which is to doublecheck which is
the green ground wire in the NEMA 6-20P (g) to mate with the white
ground/neutral in the NEMA 10-30R (w) via the NEMA 6-20R-to-NEMA 10-30P
adapter.

As noted elsewhere, you'd be better served to go to 20A breaker/plug and
junk the adapter, though...

Your chart has little W's and G's and "X" and "Y" for the hot black wires.

I presume the "w" stands for white, does it not?

Strictly speaking, it's "neutral"; but conventional (USA, anyway) wiring
is white for neutral, yes.

--