From the pattern description:

These dainty ladies will hug your feet all the while showing off a bit of fancy footwork, from lace eyelets which travel down the heel of the sock, making them absolutely perfect for clogs or sandals, to arch-hugging shaping which curves around the instep for a snug but energizing fit. Despite the dainty lace details, the addition of ribbed columns on a backdrop of reverse stocking stitch creates a stretchy fabric and provides for a custom fit. Knit top-down, grafted toe.