Tag
type: Class
comment: A tag consists of two items, a key and a value. Tags describe specific features of map elements (nodes, ways, or relations) or changesets. Both items are free format text fields, but often represent numeric or other structured items. Conventions are agreed on the meaning and use of tags, which are captured on this wiki. Though in some relatively minor cases there are competing visions what tags actually mean, or mappers using them in a different ways.