Help with mittens pattern?

[hennrietta]

http://purlbird.blogspot.com/2011/02/your-mittens.html

I'm working on the pattern linked above. But I'm not sure if I'm reading the pattern correctly or if she forgot some information, but this is the part I'm having trouble with.

"Begin Gusset:
Row 1: K12, pm, M1, K2, M1, pm, K to end.
Rows 2&3: Knit.
Row 4: K to m, M1, K4, M1, K to end.
Rows 5&6: Knit.
Repeat as established: Increasing every third round. The number of stitches between M1s will increase by 2 for each increase round. Final gusset increase round will be:
K to m, M1, K12, M1, K to end.
Knit 5 rounds plain."

Can anyone tell me exactly what I'm supposed to be repeating... or how many times I'm repeating it? I'm on the first row of the gusset part, and I don't want to continue until I know exactly what I'm doing.

For some reason or another I can't post a comment on her blog, but I did leave a comment on her mittens pattern on Ravelry.

[RochesterKnitter]

You are making an increase for the thumb. What you are repeating is a/the three row pattern. The 1st round with the M1 increases the 2nd and 3rd are knit.
Written in its entirity the pattern is as follows.

Begin Gusset:
Row 1: K12, pm, M1, K2, M1, pm, K to end.
Rows 2&3: Knit.
Row 4: K to m, M1, K4, M1, K to end.
Rows 5&6: Knit.
Row 7: K to m, M1, K6, M1, K to end
Row 8&9: Knit
Row 10: K to m, M1, K8, M1, K to end
Row 11&12: Knit
Row 13: K to m, M1, K 10, M1, K to end
Row 14&15: Knit
Row 16: Knit to m, M1, K12, M1, K to end
Row 17-21: Knit