A short web article by Ralph Griswold on ways to represent sets of neighborhood constraints used to define patterns. It covers graphical forms (template images and a 32-cell bar), textual forms (5-bit binary strings and 32-bit strings), and numerical base-10 codes. Plain weave serves as the running example, with constraint codes 15 and 16 and a 32-bit code of 98305. It is the third part of a series on constrained patterns.