Mr. Mouse here...
Lets talk about tartan pattern setts (the repeated pattern). In tartan weaving notation these are represented by a letter and number combination to describe the order that both the warp and weft yarns will be woven. Generally the notation will indicate the order of a 'half sett'. At the beginning and end of the half comes the pivot, where the end groups are shared between the current half and a mirrored half. So when you make it to the end of the notation row, you start reading it backwards to complete the full sett. Be careful not to count the last groups twice as, again, these are shared between the halves and eventually another sett. That all sounds a bit complicated, but it isn't so bad.
My half sett can be expressed as L12R4L56B56R4L4R4L4R8. L stands for black, R for red, and B for blue. The number following each letter is the number of warp threads in that grouping, so this means 12 black threads, followed by 4 red, then 56 black, the 56 blue and so on. At the end of the notation we will 'pivot' and go back the previous direction. So when we get to L4R8 (4 black threads, 8 red threads) we would continue with L4R4L4R4B56L56R4L12. Notice how we don't get a second set of 8 red threads? When then moving on to another half sett we would work the pattern forwards again but skip the L12 as it is also shared.
Before making the full kilt I want to test weave a swatch. This swatch will show me how much the fabric will shrink in the wash, and give me an idea of how well the yarn works in this application. I plan to weave about 5 yards in my test which should provide a great sample, my eventual waistband for the kilt, my fancy sock flashes, and perhaps have enough left over for a scarf. I'll be covering the math and actual process of counting, warping, and slaying in a later blog post while warping on the actual kilt fabric, but here is a picture of the full sett on the warping reel.