Editing HO scale (section)

===Scale===
[[File:N&W model @ Crewe.JPG|right|thumb|HO scale steam locomotives at the [[N&W]] RR museum in [[Crewe, Virginia]].]]
HO is the most popular model railroad scale in both continental Europe and North America, whereas [[OO scale]] (4&nbsp;mm:foot or 1:76.2 with 16.5&nbsp;mm track) is still dominant in the United Kingdom. There are some modellers in the United Kingdom who model in HO scale and the British 1:87 Scale Society was formed in 1994.

In continental Europe, H0 scale is defined in the ''{{lang|de|[[Normen Europäischer Modellbahnen]]}}'' (NEM) standard "NEM 010" published by [[MOROP]] as exactly 1:87.<ref name="nem-010-2014" /> In North America, the [[National Model Railroad Association]] (NMRA) standard "S-1.2 General Standard Scales" defines HO scale as {{convert|3.5|mm|abbr=on|4}} representing {{convert|1|ft|mm|1|adj=pre|real}}{{snd}}a ratio of {{overline|1:87.0|857142}}, usually rounded to 1:87.1.<ref>{{cite web|url=http://nmra.org/sites/default/files/standards/sandrp/pdf/S-1.2%202009.07.pdf|title=S-1.2 Standards for Scale Models|date=July 2009|work=NMRA Standards |url-status=live |archive-url=https://web.archive.org/web/20231003015659/https://www.nmra.org/sites/default/files/standards/sandrp/pdf/S-1.2%202009.07.pdf |archive-date= Oct 3, 2023 }}</ref> The precise definition of HO scale thus varies slightly by country and manufacturer.

[[File:Mercedes-O302-Joy Toy.jpg|thumb|Advertising gift of a Mercedes bus in HO]]
In other hobbies, the term HO is often used more loosely than in railroad modeling. In [[slot car]] racing, HO does not denote a precise scale of car, but a general size of track on which the cars can range from 1:87 to approximately 1:64 scale. Small plastic model soldiers are often popularly referred to as HO size if they are close to {{convert|1|in|mm|spell=in}} high, though the actual scale is usually 1:76 or 1:72.

Even in model railroading, the term HO can be stretched. Some British producers have marketed railway accessories such as detail items and figures, as "HO/OO" in an attempt to make them attractive to modelers in both scales. Sometimes the actual scale is OO, and sometimes the difference is split (about 1:82). These items may be marketed as HO, especially in the US. In addition, some manufacturers or importers tend to label any small-scale model, regardless of exact scale, as HO scale in order to increase sales to railroad modelers. The sizes of "HO" automobiles, for example, can vary greatly between different manufacturers.