Maps of where in the space of parameters for the substitution systems on the facing page the patterns obtained overlap the region indicated in the icon at the top left of each picture. Black corresponds to complete overlap, while white corresponds to no overlap. The maps shown can be thought of as being made by taking an infinitely dense limit of the array of pictures on the facing page, but keeping only what one sees in each picture by looking through a peephole at a particular position relative to the original stem.