A simple shape grammar generating Celtic knots is presented producing spirals, step patterns and key patterns in the style. The third vignette in the series shows the seamless editing of Celtic knot pattern with the addition of two new shape rules that seemingly unite a knot between a single loop and the alternating loop horizontally and vertically to produce new designs in the language. As before in this series, the shape rules apply to shapes composed of arcs and straight lines under isometry transformations.