Ta Da ---->
For Housel Positioning the center comb will look like this on both sides:
The yellow areas are the cell walls on the side you are viewing, the darker colored areas, in this illustration are what you see with back lighting, the base of three adjacent cell walls from the opposite side. Notice how they appear the same no matter which side of the comb you are viewing. Housel positioned combs, adjacent to this, "center comb" are oriented so their opposite sides are oriented opposite their compliment, this is not so with the center comb.
For Housel Positioning the center comb will look like this on both sides:

The yellow areas are the cell walls on the side you are viewing, the darker colored areas, in this illustration are what you see with back lighting, the base of three adjacent cell walls from the opposite side. Notice how they appear the same no matter which side of the comb you are viewing. Housel positioned combs, adjacent to this, "center comb" are oriented so their opposite sides are oriented opposite their compliment, this is not so with the center comb.