Changes between Version 16 and Version 17 of Help/Concepts/Object
- Timestamp:
- 2011-12-16T18:59:03+01:00 (14 years ago)
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Help/Concepts/Object
v16 v17 20 20 21 21 === Relations === 22 [[Image(source:trunk/images/data/relation.png)]] A **relation** is an sequence of other objects, for instance a sequence of [[Image(source:trunk/images/data/way.png)]] **ways** (representing road segments) and [[Image(source:trunk/images/data/node.png)]] **nodes** (representing bus stops) which represent a bus route. Each object participating in a [[Image(source:trunk/images/data/relation.png)]] **relation** can be assigned a **role**, for instance `stop` for a bus stop in the bus route, or `forward` for a road segment which is part of the bus route from the start to the terminal station.22 [[Image(source:trunk/images/data/relation.png)]] A **relation** is an sequence of other objects, for instance a sequence of [[Image(source:trunk/images/data/way.png)]] **ways** (representing road segments) and [[Image(source:trunk/images/data/node.png)]] **nodes** (representing bus stops) which represent a bus route. Each object participating in a [[Image(source:trunk/images/data/relation.png)]] **relation** can be assigned a **role**, for instance `stop` for a bus stop in the bus route, or `forward` for a road segment which is part of the bus route and which is only used in forward direction. 23 23 24 24 == Tags == 25 25 A **tag** is a name/value pair assigned to an object. Tags are used to describe an object in detail. If we write `foo`=`bar` we mean ''The tag with key foo is assigned the value bar''. Here are some examples: 26 * `name`=`Main road` assigned to a '''way'''. This tag indicates that the name of the way is `Main road`.27 * `amenity`=`restaurant` assigned to a '''node'''. This tag indicates that the'''node'''represents a restaurant in the real-world.28 * `route`=`bus` assigned to a '''relation'''. This tag indicates that the relation represents a bus route.26 * `name`=`Main road` assigned to a **way**. This tag indicates that the name of the way is `Main road`. 27 * `amenity`=`restaurant` assigned to a **node**. This tag indicates that the **node** represents a restaurant in the real-world. 28 * `route`=`bus` assigned to a **relation**. This tag indicates that the relation represents a bus route. 29 29 30 30 Tags can be combined. An object can carry as many tags as necessary. Here's a more complex example:
