The illustration for terminating lines looks like the only one I remember ever seeing, so it got my curiosity up to check some older rule books. I need to get by act together on my library because I know I have some "recently" old rule books for as long as I have been an AMA member and they used to send them out with each revision or provide one when asked. The only one I could find easily was from 1964 but I thought it might cover it, but it didn't. It goes into line lengths and diameters for the various events and such. The odd thing I found was in the Team Race rules, where they had 3 diagrams. two were for the set up and measurements for up to 3 up racing, where the take off area should be and where the "pits" should be, and it also had a diagram for a launching stooge for simultaneously launching modes for a race!! It's just an end view but shows what we typically use for a stooge that has a spring loaded release pin that grabs a loop at the back of a model. I think this is the oldest mention of a launching stooge I have ever seen.!
But back to the subject, I really don't remember anything specific for solid lines for stunt other than what's in the illustration. And a lot of guys just use heat shrink tubing to cover the wrapped section and that retains the wrapping wire. If neatly done I think this would suffice for solids also.
Type at you later,
Dan McEntee