I have never used this stitch in a cast off row before, I know it means that I have to pick this stitch up and purl into it but is that as well as purling the next stitch or together with the next purl stitch?! I’m just a novice!!
What pattern are you doing?
Are there specific directions in the pattern for this abbreviation?
As is, I can interpret it one of two ways…
- Knit 1 in the third stitch below the next stitch or
- Knit 1 below, three times
The directions are
cast off in rib across all stitches as follows:-
Work P3B into 3rd and every foll 4th st to last 3 sts
The abbreviation for P3B is purl into purl st 3 rows below
Thanks for your help
It’s a cropped lacy cardigan from a pretty girls knit pattern book 
What is the established rib pattern? 2x2, 2x3 etc
Assuming the rib is a 1x1, and the 1st stitch is a selvedge, the rib pattern on the BO row would be…
slip, k, p3b, k, p, k, p3b, k, p, k, p3b…
Adding in the BOs, you would work…
slip, k, BO, p3b, BO, k, BO, p, BO, k, BO, p3b, BO, k, BO, p, BO, k, BO, p3b…