Here http://share.ovi.com/media/currentre...resident.10166 is a photo of a triple made with a 40 tooth tuff neck and a 43 tooth pro neck chainring. The inner bolts run through all 3 chainrings. The 40 tooth is countersinked as an inner chainring and the 43 tooth is counteredsinked as an outer if one of the chainrings is reversed both sets of holes won't line up. You could just use the middle chainring to attach the inner however it won't be as strong. The chainrings are still made under different names and go up to 48 teeth.
Spec' Tarmac (road), Spec' Secteur Disc (commuter & tourer), Salsa Mamasita (MTB), CoMo Speedster (tandem), Surly Big Dummy (cargo), Airnimal (folder), a train pass, and NO car :)
What's the point? When bikes only had 5 or 6 gears on the back, half-step setups on the front were useful. Now that most bikes have 8-11 gears on the back, it doesn't seem like there is much point to having such gearing combinations up front.