Swarf - back rib 2x2

I am working the Swarf and need some help with the start of the back.
Pattern reads
Co 52 Beg 2x2 rib; work even in pattern
It doesn’t say how many rows for rib and btw there was no rib on front so don’t think there an a rib
The pattern across the row sb multiples of 16 stitches. Knit 16 purl 16 knit 16 leaves 4 stiches
Are these worked in rib all the way up the side of the back.
Thanks for any assistance
Erin