This is a stitch that is highly under utilized. It is produced with very little hand manipulation, can be produced on all knitting machines, and solves a problem of added weighting of the bottom edge of a garment.
The applications are numerous. Bottom edges of sweaters, hats and scarves, neckline edges, sleeves, body of shawls etc. The configuration of the mock rib can be 1×1, 2×2, 2×1, etc…… any combination that you can think up.
Simply, it is a combination of needles in work and others out of work across the needlebed. jjojjojjo, jojojo, jjjjjojjjjjo, etc.
Sometimes, it is knit and then folded up and the cast-on edge is hung onto the stitches that are already on the needles.
i.e on a hat. Knit 1×1 setup and knit 30 rows, then hang up cast-on edge onto the empty spaces on the needle bed as in the photos, continue to knit as you choose, with all needles in work or continue with the Mock Rib set up.
A few samples.
Yet Another Canadian Artisan, Mary Anne Cutler 2019