I have found a (very) strange way to decode a part of it. Could it be possible that TCs have no simple way to express tan? they speak of cosine (in fact cos-1), but no sine and no tan. so a possibility could be G GXhgDADghXG tan-1 (X/2) = [30] = 18 = 30degrees GQBEBQfXfpG p = 10X with X = 0.57735 from up line G...G p = 11.5470 G I agree, it is very strange, and I don't see how it could work with next 3 lines. Or maybe it is a way of showing something on some circles. Kind of astronomical coordinates? We should not forget that these 2 series of 3 lines are linked with drawings coming after them (in the same big couple of G's) or maybe they are completely separated by a double G (but it is less probable for me)