in HOn3 or OOn3 – widely used in the United States – the track is . In the United States the NMRA have developed many standards for narrow-gauge modelling, including those modelling in HOn30 and its related gauges. Summary Table The following table lists the most popular narrow gauges in HO and OO scale: Remarks Model railroaders with layouts and rolling stocks by American standard and usually by British standard use for designation of the scale in English language publications the letter O and not the number 0. In Great Britain and rarely in the French language for narrow gauge it is written after designation of the scale the model gauge in mm, for example, OO9 or OO6.5 in United Kingdom and H09 rather than H0e or H06,5 rather than H0f in France. In Great Britain and in the French language it is written sometimes with a hyphen or en dash between the scale and the model gauge, for example, OO–9 or H0-9. See also OO9 gauge narrow gauge railways in OO scale on N () gauge track in 1:76 scale ratio List of narrow-gauge model railway scales References Model railroad scales 30 inch railways and modelling Narrow gauge railway modelling