I'm making the Bernat Camouflage Child’s Cardigan (http://www.bernat.com/data/pattern/pdf/instruction_201.en_US.pdf) and I'm questioning where to measure from for the instruction in bold below

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With smaller needles, cast on 75 sts. Work 2 ins in (K1. P1) ribbing. Change to larger needles and proceed in stocking st for 15 ins, ending with a purl row.

Is it really saying to measure the 15 inches just for the stockinette part? I'm so used to measuring from the beginning of work for stuff, that I need to be sure here. Will it be 17 in total (with the ribbing), or 15 total?

I would think it means to knit 15 ins. in stockinette. I think it would have said "from beginning" if it meant the ribbing also.

That's the way I read it. I believe it meant from the beginning it would say "from cast on edge".