Datum call out on a hole

[FrancoisY]

Hello all,

I am fresh to GD&T and was wondering what a datum on a hole represents and what does it describe back to me. Image below

 

[Garland23]

Although it's touching the wall of the hole, the "datum" is the imaginary, perfect axis (center) of that hole.
And, depending on how that datum C is referenced in a tolerance frame somewhere, the axis may have to be oriented to other datums such as A or B.