Correct, although even if the chains/wires are supporting weight, their shapes for the free portions should still be _sections_ of catenaries. Thus, even the parabolic shape on a typical (Golden Gate-style) suspension bridge is a piecewise approximation from bits of catenary shapes. I hadn't realized it until I did some searching a few years ago, but the people most interested in catenaries on a day-to-day basis are people on ships who have to worry about the lengths and stresses on anchor chains. At 01:03 PM 3/18/2013, Michael Kleber wrote:
Are you talking about the chains holding up the light? There's a vertical chain as well, so the "mathematically correct" shape depends on the relative tensions of the chains. As long as the bill matches reality, catenary vs. parabola is irrelevant.
http://0.tqn.com/d/dc/1/0/C/J/whitehouse2.jpg
--Michael