Interlocking ‘Y’s (pattern)

A blackwork pattern made up of straight and diagonal stitches, giving a slightly more open structure where the individual shapes overlap. It is suitable for more architectural shapes.
Further Reading

Method
Working vertically, fill the area with columns of running stitch four fabric threads apart. Work each running stitch over two, and under two fabric threads.
Working horizontally, make pairs of diagonal stitches slanted in alternate directions to form arrowheads. Each stitch should cover two intersections of the fabric.
The point of each arrowhead should be inline with the top of each running stitch. The direction of the arrowheads should alternate, pointing either up or down. Where they point down, they should join the running stitch.
Continue working horizontally back and forward across the area to keep adding pairs of diagonal stitches in the spaces between the running stitches.

Embroidery Techniques
Related Stitches
References
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Becky Hogg, RSN Essential Stitch Guides: Blackwork (2010)
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Various Authors, The Royal School of Needlework Book of Embroidery (2018) , p.143