From: utzoo!decvax!ucbvax!CAD:quarles Newsgroups: net.railroad Title: Re: Re: HO scale query - (nf) Article-I.D.: ucbcad.148 Posted: Thu Dec 9 16:09:01 1982 Received: Sat Dec 11 08:24:59 1982 #R:rocheste:-29800:ucbcad:29000003:000:529 ucbcad!quarles Dec 9 16:08:00 1982 What is HOn3 and HOn2-1/2? I saw these in an issue of Model Railroader. These are terms used for referring to narrow gauge railroads. A standard gauge railroad is (I think) 4 feet 9 1/2 inches center to center between the rails, and standard HO scale models this with rails spaced 1/87 of this distance (approx. 18.7 mm) apart. HOn3 is a model based on a narrow gauge prototype with a 3 foot center to center rail spacing. Similarly, HOn2-1/2 models a narrow gauge prototype with a 2.5 foot center to center rail spacing.