900 mm (2 ft 11 7⁄16 in) narrow gauge railways are generally found in Europe. This gauge is mostly used for light urban rail networks, industrial and agricultural railways.
900 mm gauge railways Wikipedia
In Sweden there has been an extensive network of railways with 891 mm (2 ft 11 3⁄32 in) gauge, Swedish three foot gauge railways. Some of them remain. This is so close to 900 mm (2 ft 11 7⁄16 in) that they are more or less compatible, and some sales of rolling stock between the gauges have taken place.