OpenStreetMap Semantic Model (tags)

1. Tags

In OSM, tagging is the process of assigning descriptive metadata to geographic features (such as roads, buildings, and natural features) drawn before on the map. This metadata is used to describe the attributes and characteristics of the feature, such as its name, type, size, and other relevant information.

Every feature must be described at least by one tag. The number of tags needed to describe a feature in OSM varies depending on the complexity of the feature and the level of detail required. Some features may only require a few basic tags to describe their type, while others may require dozens of tags to accurately capture all of their attributes.

The correct way to tag features in OSM involves using a specific syntax and following established conventions for each type of feature. This ensures consistency and compatibility with other OSM data and helps to maintain the quality and accuracy of the map.

To tag a feature in OSM, you need to specify the feature's type (e.g. highway, building, natural), and then add a series of key-value pairs that describe the feature's attributes. For example, to tag a secondary school in OpenStreetMap, you can use the following key-value pairs:

amenity=school

school=secondary

This assigns the key "amenity" with the value "school" to indicate that the feature is a school, and the key "school" with the value "secondary" to indicate that it is a secondary school.

In addition to these basic tags, you can also include other key-value pairs to provide more detailed information about the school, such as its name, address, telephone number, website, and so on:

amenity=school

school=secondary

name=Name of the Secondary School

address=Address of the School

phone= phone number of the School

website=http://www.secondaryschool.com

To tag a building:

building=yes

This assigns the key "building" with the value "yes" to indicate that the feature is a building. In addition to this basic tag, other key-value pairs to provide more detailed information about the building can be added, such as its name, type, address, and so on:

building=yes

building:levels=4

building:material=brick

name= name of the building (if any)

address= address of the building

The "building:levels" tag specifies the number of levels or stories in the building, and the "building:material" tag specifies the material of which the building is constructed. The "name" tag specifies the name of the building, and the "address" tag specifies its address. It is also possible to add more detailed information about specific parts of the building, such as entrances, windows, and so on. This can be done using tags such as "entrance", "window", "roof", and so on.

To tag a road as a primary highway, you would use the following syntax:

highway=primary

and then you can add much more specifications.

There are many established conventions for how to tag different types of features in OSM, and these are documented in the OSM Wiki. The conventions cover everything from basic features like roads and buildings to more complex features like transit systems and land use.

2. Conventions and Wiki

It is important to follow the established conventions as closely as possible when tagging features in OSM. This helps to ensure that your data is accurate, consistent, and compatible with other OSM data, making it more useful for everyone who uses the map.

For questions related to tagging, the best way to get help is to use the OSM community resources available online.

Here are some of the most popular websites where you can find information about how to tag in OSM:

1. The OpenStreetMap Wiki: This is the official wiki for OpenStreetMap and contains a wealth of information on how to tag various features in OSM. The wiki is constantly updated by the OSM community and is a great resource for learning about tagging conventions, best practices, and other aspects of mapping in OSM. You can access the OSM Wiki at https://wiki.openstreetmap.org.

2. Taginfo: This is a website that provides a simple interface for searching and browsing OSM tags. You can search for a specific tag or browse by tag category to learn more about how to tag different types of features in OSM. It also provides statistical information about OSM tags, including how often they are used and which features they are used to tag. Taginfo is a useful tool for understanding the prevalence and popularity of different tags in OSM. You can access OSM Tags at https://taginfo.openstreetmap.org/.

3. Map Features: This is another website that provides information about how to tag different types of features in OSM. Map Features provides a comprehensive list of feature types, along with recommended tags and descriptions for each type. You can access Map Features at https://wiki.openstreetmap.org/wiki/Map_Features.

3. Mailing list

Another option is to use the OSM mailing lists, which are email-based discussion forums where OSM contributors can ask questions, share information, and discuss various topics related to mapping in OSM.

The most appropriate mailing list to contact for questions related to OSM tagging is the Tagging mailing list. This list is dedicated to discussions about OSM tagging and is a great resource for getting help with specific tagging questions, discussing tagging conventions and standards, and staying up-to-date with changes to OSM tagging.

Here is the link for subscribing to the Tagging mailing list: https://lists.openstreetmap.org/listinfo/tagging