Bricked wave (pattern)
Start by stitching a horizontal row of running stitches over four threads and under one thread of the fabric.
Stitch a parallel line two fabric threads below, ensuring each stitch is in line with the previous row.
Work across the shape again, with a vertical stitch over two fabric threads to join the horizontal lines at alternate ends. Concentrate on a column at a time and zig zag across the shape.
Structure of stitch
Various Authors, The Royal School of Needlework Book of Embroidery (2018) , p.152
Becky Hogg, RSN Essential Stitch Guides: Blackwork (2010) , p.76