This is based on the right hand panel of pattern 80 in "Japanese Knitting Stitch Bible" by Hitomi Shida, page 49. I have inserted all purl wrong side rows.

Work the yarnover which comes after a purl and before a knit stitch by passing the yarn clockwise round the right-hand needle; i.e. pass the yarn between the needles to the back, bring it to the front over the right-hand needle and finally pass it back between the needles ready to knit the next knit stitch. The usual way of performing this yarnover is to bring the yarn over the right-hand needle to the front, but this produces a very small yarnover. The method described helps prevents yarnovers being of different sizes.

The panel can be repeated to make an overall half-drop pattern, see here.

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