Oh yes,of cause - Those pesky Letters...I am not certain at all on those but what I notice is that with each Letter there is a corresponding Colour associated and as you go up the table the Numbers increase - I am not sure at all,I think that is a question for Hugh as he introduced me to that page.

Along the Bottom of that table is listed (S)outh (W)est (N)orth (E)ast - If I stare at it for long enough the penny might eventually drop,but alas that may take Minutes to Days so I shall not be attempting that(I have done similar with many strange graphs/tables Lmao!)

No,I think it best to wait for Hugh on that One,or One of our other Folks out there to answer that : )