Spiral Rib Sock question

[MommaRalph]

Hi! I am working on these spiral rib socks:
http://www.knitlist.com/95gift/super.htm

"Cast on 48 stitches and join work on doubled pointed needles. Do Knit 3, Purl 3 ribbing for 4 inches. Begin next round with P1, K3 and continue in K3, P3 ribbing. Work 3 more rounds. Begin next round with P2, K3 and continue in K3, P3 ribbing. Work in this manner, moving the rib stitches over one stitch every four rounds. (Don't worry about screwing this up - I've noticed that if you use dark yarn you don't notice as much if you begin the next round one row late or early.) Work until sock is about 16 inches long total."

I do OK till I get to the red type. I P1, then do more ribbing for 3 more rows, then I P2 and continue in ribbing for 3 more, P3... but then what? P4 to start? Then P5? When does this end? I'm gonna have a spot that is all purl stitches, aren't I? I'm thinking I eventually Knit at the beginning of a row before Purling? Can anyone help here? I think that maybe I work in the K3, P3 ribbing pattern kinda changing the starting point of the rows? Does my question even make sense?

Thanks!
Valerie

[Ingrid]

In order to get the spiral effect, you're shifting your ribbing.

So all along you've been working

kkkpppkkkpppkkkpppkkkppp
kkkpppkkkpppkkkpppkkkppp for 4 inches. Now shift
pkkkpppkkkpppkkkpppkkkpp for the next 4 rounds, then

ppkkkpppkkkpppkkkpppkkkp 4 rounds each

pppkkkpppkkkpppkkkpppkkk

kpppkkkpppkkkpppkkkpppkk

kkpppkkkpppkkkpppkkkpppk

kkkpppkkkpppkkkpppkkkppp

See the pattern?

[MommaRalph]

Got it! Thanks!