Threads have been cut and removed. In this case, I cut and removed two, left four, cut two, and so on both vertically and horizontally. Next I worked the mosaic filling stitch. Moyra McNeill describes it as "basically a square, bounded on each side by blocks of 5 satin stitches over 4 threads".
In that it is 5 satin stitches over 4 threads, it is very like the kloster blocks in Hardanger, but here it is done as a pulled-thread stitch. Pulling each satin stitch tightly compresses the 4 threads underneath and opens up the square's center a bit more.
The next step deals with the areas within the squares. But that will have to wait.