have got to the shading stage but can't see any coordinates - is it symmetrical? I know what the yellow bit is and I presume the 43 provide the framework around it, or are they all the other cells not in the middle part?
I presumed the 43 were made up of the 32 yellows + 11 in a zig zag pattern above?? Could be totally wrong though?!
..or perhaps the 43 cells are the "other" cells from the top 5 rows ?