1. I have a surface in three-space, and am looking for a term to describe if it's possible to determine which side a viewer is on. I was thinking about the 33336 tiling, how viewed from one side it has a left twist, and the other side has a right twist, so I thought chiral vs. achiral would work, but if I have a surface that is all black on one side, and all white on the other, compared to one that is white on both sides, that terminology is wrong. So is there a term to describe if a surface looks the same from both sides, or has a different appearance.
2. In a tiling, if A and B both belong to the same Transitivity class, is there an equivalence term to say that. When I've been writing I've been saying that A and B are Transitive, but I'm not sure it that's valid, or correct, so I want to make sure before I use it any more.