From the Stitch Description: There are really two chains, interlocked with each other, in this pattern--a dark one on a light background, and a light one on a dark background. Thus the pattern is nothing but a single variation on slipped vertical stripes.

Note: On all right-side (odd-numbered rows, slip all sl-sts with yarn in back.

Location of Stitch: Chapter Four (Mosaic Patterns), page 66 from A Second Treasury of Knitting Patterns