A short web document by Ralph Griswold introducing line-based patterns, in which one basis line is transformed row by row (by cyclic permutation, reversal, complementation) to generate grid-plot patterns. It explains binary sequences and binary indices for identifying a line (e.g. 8:59), design-equivalent patterns, and how to find a fundamental basis line with a worked example (8:19). It includes a table of the number of fundamental basis lines for lengths 2 to 16 and notes that soundness of the resulting interlacements must be treated separately.