FWIW...

From Nova Cycles Supply: http://www.cycle-frames.com/bicycle-...g/TUBES-STEEL/

"The painted end of a tube is the SHORT BUTT SIDE. Make your minimum cut from this side and your adjusting cut on the opposite side."

And from Henry James: http://www.henryjames.com/butt.html

"Tubes with unequal double butting are marked with paint at one end. An asterisk (*) in the chart shows where the tube is marked.

Double asterisks (**) show where external butting occurs."