Help with a pattern

I’m trying to knit the back section of a cardigan that has striping. The instructions say,

Attention: the following instructions must be worked at the same time:

Work straight until work measures 4 1/2 from CO edge, (measured along sleeve) break yarn and change colors

Work straight until work measures 3 1/2 from CO edge

Then it goes into the armhole shaping

I’m so confused…do I start the armhole at the same time, the color? The inches … please anyone help! What am I working at the same time…

Welcome to KH. What pattern are you using? I can’t answer your question, the instructions confuse me too, but someone will be able to help.

I think we’d need to see the pattern as I’m not surprised that you are confused!! You’re knitting the back but are measuring along the sleeve? As you progress your knitting, the distance from the cast on edge gets shorter?
Is it an unusual garment construction? Is it a paid for pattern? Sometimes free patterns haven’t been edited very well and contain multiple errors.
It would help to see a picture of the proposed cardi!