Understanding a knitting pattern

I started knitting a jumper on Friday and have already finished the back and started the front.  The pattern is very easy for the most part as there is no waist shaping.  It's a mass of 4 by 2 rib up to the raglan shaping but I did trip up a bit on the instructions. 

Here is the line:
Work 10 rows dec 1 st at each end of 1st and every following 2nd row.

At first I couldn't fathom it. Then I thought it meant decrease on rows 1, 2, 4, 6, 8 and 10 and wondered why it would have me be bonkers and decrease on wrong sides in such a seemingly random fashion.  I checked how many stitches would be decreased overall - from 86 down to 76 = 10 stitches.  So that's two stitches each on five rows.  Lightbulb! It means decrease on the RS rows only.  It's funny how a slightly different phrasing can throw me off, but having deduced it I was back in the game.