Open zigzag (pattern)
A blackwork pattern made up of rows of zigzag lines stitched diagonally over the fabric, with an added horizontal stitch at each point. It is a mid-scale pattern and is suitable for creating a geometric effect within more linear shapes.
Make a horizontal stitch over two threads them bring the needle up diagonally two threads above
Complete a back stitch into the same hole the previous stitch ends and then bring the needle up at the end of that stitch so that the thread on the back is obscured by the last surface stitch
Structure of stitch
Various Authors, The Royal School of Needlework Book of Embroidery (2018) , p.147