Editing O scale (section)

===Scale and gauge===
[[Scale (ratio)|Scale]] refers to the size of the model relative to the actual full-sized object being represented, while [[Rail gauge|gauge]] is the width of the model track. Most commercially produced model track is a compromise between appearance and a trouble-free running surface.

====Scale====
Scale is the ratio of a model dimension to the real life dimension. O Scale in the UK is commonly 1:43.5 or 7&nbsp;mm to the foot. In continental Europe it is commonly 1:45. 1:43.5 is also used, particularly in France.<ref name="NEM-010">{{cite web|url=http://www.morop.org/fr/normes/nem010_f.pdf|title=Normes Européennes de Modélisme: Rapports de réduction, échelles, écartements|year=2004|publisher=Union Européenne des Modélistes Ferroviaires et des Amis des Chemins de Fer|language=FR|access-date=2010-04-11}}</ref> In the USA, 1:48 is common.<ref name="NMRA S-1.2 2009.07"/> The [[National Model Railroad Association|NMRA]] and the [[MOROP]] maintain detailed standards for a variety of scales to help model makers create interoperable models.<ref name="NEM-010"/><ref name="NMRA Intro">{{cite web
 |url          = http://www.nmra.org/standards/standards.html
 |title        = Standards & Recommended Practices - Introduction
 |date         = 2008-02-17
 |author       = T.J. Klevar
 |access-date  = 2010-04-11
 |publisher    = [[National Model Railroad Association]]
 |url-status   = dead
 |archive-url  = https://web.archive.org/web/20100403082408/http://www.nmra.org/standards/standards.html
 |archive-date = 2010-04-03
}}</ref>

====Gauge====
''Gauge'' refers to the distance between the inside edges of the load-bearing rails. Various sizes of [[track gauge]] exist around the world and the normal O gauge track represents the [[Standard gauge]] of {{Track gauge|1435 mm}}. "O gauge" refers to tracks that are nominal {{Track gauge|32mm}} according to older standards of NMRA, current standards of BRMSB and NEM. {{Track gauge|1.25 in}} apart current standards of NMRA.<ref name="What is O Gauge"/> When used as a [[narrow-gauge]] track, O gauge allows scales such as 1:32 representing {{Track gauge|1000 mm}} gauge track. 1:20 representing {{Track gauge|600 mm}} [[narrow-gauge railway]]s.

Regional model manufacturers design their O-scale rolling stock with minor regional scale differences—manufacturers support their rolling stock with track made to the same regional scales, so there is no universal width for O-gauge model track.{{Citation needed|date=April 2010}} Models could represent the real-world standard gauge track spacing of {{Track gauge|1435 mm|disp=1}} by choosing various spacings such as {{Track gauge|30 mm}} at 1:48 scale, {{Track gauge|1.25 in}} at 1:45.2 scale, {{Track gauge|32 mm}} at 1:44.8 scale, {{Track gauge|32.96 mm}} at 7&nbsp;mm:1&nbsp;ft scale, and {{Track gauge|33 mm}} at 1:43.5 scale. Model makers choose their scale based on many considerations including the existing marketplace, aesthetic concerns and compatibility with existing models.

====Wide- or narrow-gauge track====
[[File:Spur 0e Zahnradbahn im Modelleisenbahnclub Basel mit He 2 2 und Vorstellwagen 2021.jpg|thumb|Probably the oldest known 0e gauge vehicles in the MCB from 1947. WAB rack railway train, 2021]]
Some O-scale modelers choose to model prototypes at other than standard gauge and follow wide gauge (also known as [[broad-gauge]]) or [[narrow-gauge]] railroads. There is no standard for wide- or narrow-gauge model track, and modelers wishing to portray such railway track either build their own, or more commonly accept the shortcomings of appropriately wider or narrower gauge model track. {{Track gauge|16.5mm}}, {{Track gauge|12mm}} and {{Track gauge|9mm}} are the more popular track widths used by indoor enthusiasts modeling narrow gauge. Differences in regional scales give different prototype gauges to these different model track widths.

For example, using specially manufactured {{Track gauge|16.5mm}} gauge track, scaled at 7&nbsp;mm to the foot (with appropriately spaced, larger [[Railroad tie|sleepers]], etc.) underneath:
# UK O scale rolling stock (1:43.5), it becomes a narrow-gauge track of {{Track gauge|2ft4in}}, and is referred to as "[[On30 gauge|O&nbsp;16.5]]". Modelers portray gauges between {{Track gauge|2ft}} and {{Track gauge|3ft}}.
# European O scale rolling stock (1:45 or 1:43.5 in France), it becomes a narrow-gauge track of {{Track gauge|750mm}}, and is referred to as "[[Oe gauge|Oe]]" portraying a {{Track gauge|750mm|disp=1}}, {{Track gauge|760mm|disp=1}} and {{Track gauge|800mm|disp=1}} prototype. Modelers portray gauges between 650 mm and 800 mm prototype.
# United States O scale rolling stock (1:48), it becomes a narrow-gauge track of {{Track gauge|2ft6in}}, and is referred to as "[[On30 gauge|On&nbsp;2½]]" (or On30, as in 30 inches).