Proposal:Segmented Tag

Note: This is currently a proposed relation, the currently agreed on method for achieving this is by splitting the way.

Tags for a Way are used given for a complete way. If a tag references only a certain part of a way, you have to cut the way into two or three ways.

A Segmented Tag references a certain part of a way, a segment. (This is not the same as a Segment of the OSM API before version 0.5!)

Tags

The tags field holds key/value pairs for all tags which shall be applied to the part of the way given by the three members of the relationship: a way and two nodes of this way specifying the way segment. The tag keys type and direction are attributes of the relationship, all other tags are attributes of the way segment.

Key	Value	Discussion
type	segmented_tag
direction	both, positive, negative	the following tags are valid for this direction (default: both)
...

Members

The following three members are specifying the way segment:

Way or Node	Role	Recurrence?	Discussion
		one	the way
	from	one	start node of the way segment (node has to be part of the way)
	to	one	end node of the way segment (node has to be part of the way)

Examples

Ways with a lot of bridges or tunnels: Instead of cutting the way in smaller way parts, specify a segment and the appropriate bridge or tunnel tag and a layer tag.

Ways with a tag having different values for each driving direction: the maximum speed can be different for different segments of a way and can be different for each driving direction. Instead of cutting the way each time the maximum speed for one direction changes, specify a segment and, if necessary, a direction with the appropriate maxspeed tag.