Category:Pl:Keys indicating lengths in millimetres
Pages describing keys that indicate lengths, typically at a small scale. These keys' values are measured in millimetres (millimeters) unless otherwise specified in a unit such as metres (meters) or feet-and-inches.
The use of millimetres for these keys is a historical anomaly, and some closely related keys are expressed in the usual metres. Therefore, mappers should specify the unit explicitly as much as possible to avoid large-scale confusion.