It says to work even in reverse St stitch for 1 1/2". It's for a section using eyelash yarn. The eyelash yarn comes out more fully on the purl side than on the knit side. Just before the reverse st stitch section, you knit one round.
According to my Reader's Digest COMPLETE GUIDE TO NEEDLEWORK, the purl side of stockinette stitch is referred to as "reverse stockinette stitch", so I am simply purling for this section in my pattern. But, why can't the instructions simply SAY "purl"?