Introductory article by Ralph Griswold on computational analysis of weave structures. It represents interlacement patterns as binary arrays (1 for warp up, 0 for weft up) and gives a step-by-step, program-style procedure for finding a pattern's unit motif by computing row and column repeat lengths and their least common multiple. It then introduces line patterns, circular permutations, canonical forms and block-length patterns, and works through an 8 x 8 example drawn from Oelsner's Handbook of Weaves, ending with a complete line analysis of the rows and columns.