Butterfly Marker Hole?

[Jack]

There used to be a good write up on the purpose of the marker hole on the left side of the butterfly assembly.
I cannot find the write up online anymore had pics and everything.
I forget the purpose of the hole for sure, but i want to say it was for setting the idle screw with the intake off.
Could someone post the link or post a copy of that write up if they know the one I'm talking about.
Thanks.

[Jack]

Reworded:
I'll try to be a bit more detailed.
The write up I'm talking about used the Throttle Edge Tapping hole as a point of reference in setting the butterfly plates.