Changes between Version 1 and Version 2 of Help/Concepts/Object

Timestamp:

2009-10-10T10:47:51+02:00 (15 years ago)

Author:

Gubaer

Comment:

Extend tags section

Help/Concepts/Object

@@ -1 +1 @@
 = Objects - The basic building blocks of OSM data and maps =
 
-JOSM helps you to enter data about real-world objects in the OSM geo-database. Despite the overhelming complexity of real-world objects you can map, JOSM provides only three kinds of objects as basic building blocks for maps: '''nodes''', '''ways''' and '''relations'''. 
+JOSM helps you to enter data about real-world objects in the OSM geo-database. Despite the overhelming complexity of real-world objects you can map, JOSM provides only three kinds of objects as basic building blocks for maps: '''nodes''', '''ways''', and '''relations'''. 
 
-You can assign '''tags''' to objects. It's the assigned set of tags which makes a node representing a restaurant different from a node representing a church, or a way representing a residential road different from a ways representing a river, or a relation represeting a bus route different from a relation representing a cycling route. 
+You can assign '''tags''' to objects. It's the assigned set of tags which makes a node representing a restaurant different from a node representing a church, or a way representing a residential road different from a ways representing a river, or a relation representing a bus route different from a relation representing a cycling route. 
 
 
 == Nodes, ways, and relations ==
 
-
  * [[Image(source:/trunk/images/data/node.png)]] - a  '''node'''  is an individual point with a defined position. 
 
- * [[Image(source:/trunk/images/data/way.png)]] - a '''way''' is a sequence of nodes. Despite its name a '''way''' doesn't represent ways in the real-world only. An OSM way is also used to respresent a river, the boundaries of a country, or even a building. If a '''way''' is closed, i.e. if the last node is the same as  the first node, it is also called an '''area'''. 
+ * [[Image(source:/trunk/images/data/way.png)]] - a '''way''' is a sequence of nodes. Despite its name a '''way''' doesn't represent ways in the real-world only. An OSM '''way''' is also used to respresent a river, the boundaries of a country, or even a building. If a '''way''' is closed, i.e. if the last node is the same as  the first node, it is also called an '''area'''. 
 
  * [[Image(source:/trunk/images/data/relation.png)]] - a '''relation''' is an sequence of other objects, for instance a sequence of '''ways''' (representing road segments) and '''nodes''' (representing bus stops) which represent a bus route. Each object participating in a '''relation''' can be assigend a '''role''', for instance `stop` for a bus stop in the bus route, or `forward` for a road segmente which is part of the bus route from the start to the terminal station. 
 
+== Tags == 
+A '''tag''' is a name/value pair assigend 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 two examples:
+  * `name`=`Main road` assigned to a '''way'''. This tag indicates that the name of the way is `Main road`. 
+  * `amenity`=`restaurant` assigned to a '''node'''. This tag indicates that the '''node''' represents a restaurant in the real-world.
+  * `route`=`bus` assigned to a '''relation'''. This tag indicates that the relation represents a bus route.
 
-== Tags == 
-tbd
+Tags can be combined. An object can carry as many tags as necessary. Here's a more complex example:
+{{{
+highway=living_street
+name=Main road
+name:de=Hauptstrasse
+maxspeed=30
+hgv=no
+oneway=yes
+}}}
+Assigned to a way, this set of '''tags''' indicate, that the '''way''' represents a living street with name ''Main road'' (the german name be ''Hauptstrasse''). Speed is limited to 30km/h and heavy goods vehicles (hgv) are not allowed. Furthermore, it's a one way street.
+
+You are free to assign an object whatever tag you feel necessary. However, there is a list of so called [http://wiki.openstreetmap.org/wiki/Map_Features Map Features], i.e. a canonical list of '''tags''' with a well-defined meaning which are often used by mappers. Whenever possible you are adviced to stick to these tags because map renderers, routing engines, and other pieces of software rely on them.
+
 
 == Object ids ==