Central Double Decreases: sl2-k1-p2sso and sl2tbl-p1-p2sso
A central double decrease eliminates 2 stitches in a symmetrical way (thus ‘central’ and ‘double’). It results in a strong vertical decrease line that doesn’t slant to the left or the right, the way that the decreases k2tog, ssk, or sl1-k2tog-psso do.