Namespace

A namespace is a prefix or suffix within a key to provide detailed information about a particular aspect of a feature. It is separated from the name key by a ':'. At a basic level within the system a key with a namespace will just be treated as any other key.

Uses of namespace

• maxspeed:forward=* (to indicate a speed limit that only applies in the forward direction for the Way.
• addr:city=Mandaluyong (to contain part of an address)
• generator:output=* (to provide information about the power output of an electricity power generating plant.
• proposed:lanes (to indicate that there is a proposal to change the number of lanes=* for a road)

Presentation

Many tags of this sort are not currently interpreted correctly by the current map presentation software and therefore won't appear on the main mapnik view but may be used by other downstream systems are often the best way to provide additional information about a feature.