From: utzoo!decvax!cca!hplabs!intelqa!omsvax!dps@sri-unix
Newsgroups: net.railroad
Title: HO scale and guages
Article-I.D.: omsvax.259
Posted: Mon Dec 13 17:28:08 1982
Received: Sun Dec 19 05:08:11 1982

HO scale is the 1/87 proportion business (O scale is 1/48, OO is a little
bit bigger than HO (I forget how much) but is chiefly British, and their
1:1 scale stuff is on the small size, so it looks like our HO)

HOn3 is HO scale, narrow gauge -- rails 3 ft apart
HOn2 1/2  is HO scale, narrow gauge -- rails 2 1/2 ft apart (a modeler's
  compromise that let's them use N scale standard gauge track)
HOn2 is HO scale, narrow gauge -- rails 2 ft apart (mostly in the Maine woods)

NOTE THAT YOU CAN ALSO HAVE:
On3 -- O scale, narrow gauge, 3 ft spread
On2 1/2, On2 etc...

Sn3 -- S scale
...

TTn3 -- TT scale

Zn3 -- Z scale

ad infinitum, ad nauseum.  The important thing is SCALE tells you how
big your ruler is, GAUGE tells you how many rulers to use.