I know its draging up an old thread, but I can answer the question on what the yellow paint is for on the tailplanes of the jag pictured in LFA7 (I would assume) is for. It's PR143 primer and its there because the paint around the rib to lower skin attachment fasteners has been removed (in Colt AMF I would wager) to see/remove/replace the pulled fasteners in these locations! In the military world, you cannot do the job and then recover the surface finish like the civilian MROs do! You had to get the painters in to do it! If they were unavailable, well prime it up and let it go flying, hopefully with a husbandry entry in the F700 to remind somebody that it needs painting! Sorry chaps, the lines mean nothing more than somebody not finishing off a job!