The carrier on my 2-tone blue PA is light blue and I seem to remember that this was the consensus approach on the Autox triple-M web bulletin board when I was about to paint my waggon back in 2000.
Its a throwback to the old bbs type of information passing. Instead of a web page type forum, ( which is coded using html and passes data usually running TCP/IP stacks, unix and PC etc) you can get data and ask questions on machines that cannot web browse but have mail, ( I forget the protocol, but old machines like VAX using decnet etc would still be able to pass data to non vax machines )