From Reversible Two Color Knitting by Jane Neighbors. Alternate reversible. This stitch has a slide after the cast-on that I am interpreting to mean that row 1 is WS for this version. Cast on in dark, row 1 in dark, rows 2 and 3 in light, rows 4 and 5 in dark, rows 6 and 7 in light, row 8 in dark. This is a stockinette/ reverse stockinette welt of 3/5 rows.
Shown with a cast-on count of 2 stitches.