Definition:Rubik's Cube/Center Facet

Definition

 * RubiksCubeFacets.png

Of each of the $9$ facets of each face of Rubik's cube, the ones in the centers of the faces are called the center facets.

The set of center facets can be denoted $S_Z$.

The set of center facets is:
 * $S_Z = \set {F, U, R, L, B, D}$