I was trying to post a picture but I guess I am not allowed since I am new, you should be able to see it in my album.

It is a round circle with a slot where you can put a coin in to turn it, the diagram below it says "after the reverse with the previous one. then under that there is a #1 with an arrow pointing to a 0 then arrow pointing to a -1.

EDIT: See pic below on the next reply

 

Trying to see if the pic comes up this time.

 

Looks like it's something you'd take out to view whatever is in there. Maybe be for an adjustment of some kind.

Maybe it's just me, but the sticker doesn't make sense.

 

that looks like the plug you pull to add oil.(to me anyways--pull it off and see what's in there).
the sticker looks like the shifting pattern if you have a heel shifter. does the shifter look like a see saw for your left foot? if so, it's a heel shifter, +1 up a gear -1 downshift.
what does your owner's manual say?

 

Thanks, The heel shifter would be the best answer. The plug itself is not for the oil, I did take it off and it's for nothing that I see anyway.

 

Normally that sloted cap is to view the position of the stator. Love that Chenglish sticker!

Joel