At least, I think it is, though it has been dismissed as rather silly by others.
This is something I picked up on from a friend as I was sorting through reams of Canadian kiloware. Many Canadian (and other countries) have stamps which are issued with one or more straight edges, and I am not talking about coils here. The only country that I am aware of that actually has these listed in Scott is Sweden.
With Canadian issues, particularly modern ones, these straight edges are generally looked upon with scorn. It's almost as if they were damaged though, in reality, they are rarer than fully perforated types.
Now, as I was bemoaning the number of these straight edge varieties I was finding, this friend told me of something he attempts to do. That was to mount "miniature sheets" of nine with one fully perforate in the centre and the nine possible straight edges around it. Sometimes impossible because not all varieties have necessarily been created. But amusing and a game I play whenever I am sorting out large batches of material.
Here are a couple of examples in progress.




