VW  CVM 1.1 
As a preview of the classification of patterns with antisymmetries, which we carry out in the next section , imagine the image above drained of colors or shadings, with only the shapes present, as if in a coloring book waiting to be filled in. That pattern is invariant under the group cmm.
One name for that patterntype emphasizes this fact. The notation of
Whichever nomenclature one uses, the main thing to understand before going on is this: in patterns with negating symmetries, one must keep track of the group of symmetries, along with a larger group that includes the antisymmetries as well. We use Shubnikov's notation here, as it indicates this pair of groups in a natural way.
This leads to the following notation. Given a function f, let us call G the largest group of isometries under which f is invariant, while E will be the largest group of isometries of the function f. (E is a mnemonic for the extended symmetry group of G; it includes all symmetries and antisymmetries of f.)
shown at the right. Here, G is pmm and E is cmm. The two names for this pattern type are p'_{c}mm and cmm[2]_{5}.
The negating diagonal half

