A big thank you to Neli (n3li) for her notes and colored chart :
OI and IO in one box are two separate stiches: a yarn over followed by a knit stitch or a knit stitch followed by a yarn over. It is written that way because the stitch count does not stay the same in every row.

As the pattern tells you the central stitch and the selvedge stitches are not charted. The chart shows the left part of the shawl and the chart has to be mirrored after the central stitch for the right part of the shawl. The nupps are knit only on the outsides of the shawl. In the center there are no nupps but knit stitches.

The yellow part of the chart is the outer part of the shawl. The part that is to be repeated is bright green and the repetitions are light green. The last repetition on row is a variation of the pattern needed to get the correct stitch count and is marked teal. The orange part of the chart is the center part of the shawl up to the center stitch.

With each repetition of the rows 27 to 37 you’ll have two new repetitions of the pattern on each side of the shawl.