Key:source - OpenStreetMap Wiki

The source=* tag can be used to state the source of any information added to OpenStreetMap. Such entries become a prominent type of metadata (data not instantly visible on the face of any particular, chosen rendering of the map), however much less specific than the list of changesets, which call for their own source to be detailed. This tag and, much more so, its sub-tags are nonetheless excellent for verification of sources of an object which is likely never to be improved upon (rare). It is useful more broadly to assist future editors who may wish to see rapidly the origins of single-predominant-feature object they intend to modify, among map data.

With modern editors, the source=* tag should typically be added and is prompted to be added, with the request "please", to the changeset when a change is made, not as a tag on any mapped piece of information which will be updated at different times based on different sources. However, the practice of tagging objects or individual attributes has not been officially deprecated and is still being used by some mappers, so don't go around deleting source tags indiscriminately.

Ideally limit your modifications thematically by the source you use so as to unambiguously attribute the source data, and allow validation very readily. If that's too much time for instance with slow/intermittent internet connection and risking failure of uploading a large changeset of data, just use the standard OSM multivalue convention of separating them with a ";" (semicolon) e.g. source=survey;https://www.mapillary.com/map/im/... (when combining information from your own surveying and a mapillary image).

How to use on changesets

When uploading/saving your edits to the public osm database, your uploads are always marked as a changeset with your username, the time of change etc. To this changeset you should add an explanatory comment and also a source=* tag how the details were captured. When you update or change an existing object (node, way, area, relation etc.), just specify the source of your changes, since the previous changesets and their sources can still be seen in the history of the object. But do mention a source even if it is the same as in a previous edit, because this is not implied (save for cosmetic improvement of a badly drawn curve/squaring of almost-90° corners will not call for any questioning of source data, for example).

Historic usage on objects and attributes

When this page was originally created, it was normal practice to put the source=* tag on the objects being edited rather than on a changeset. This section describes the specifics of that usage.

The most common way to do this old-style source-tagging is/was to simply add a source=* tag on the object being edited, such as a building or a road.

It is often preferable to use separate source tags for each of the main tags, for example source:name=*, source:ref=*, source:addr=* detailing how the information for name, ref and address information was collected.

In the Potlatch editor a source tag can be added to a feature by pressing 'b'.

How to use (historic)

Add a source tag detailing how the details were captured. Please also update the source information if you check or update a tag value based on a new survey. For example, a feature may have originally been captured from out-of-copyright imagery, being tagged 'source=NPE'. If you then later improve the alignment using Bing imagery then change the source value to 'source=Bing'. If a tag value is based on information derived from multiple sources use 'source=NPE;Bing' or similar.

Single source tag (historic)

A single source tag is used when all tags associated with a feature have the same source. For example:

1. source=survey - to indicate that all tags were added based on a survey
2. source=Bing - to indicate that all tags were added based on Bing Imagery.

Multiple source tags (historic)

If a feature has multiple tags you may want to make use of the source namespace to indicate precisely which tag your source refers to. For example:

1. source:geometry=Bing to indicate that the geometry (shape and position) of an object was based on Bing Imagery.
2. source:name=survey to indicate that the name was added based on a survey.
3. source:name=OS Locator to indicate that the name added from OS Opendata Locator.
4. source:name=massgis to indicate that the name was added from a Massachusetts open data source
5. source:addr=massgis to indicate that the address was added from a Massachusetts open data source
6. source:width=ARCore to indicate that the width of the way was surveyed with Android ARCore.

Other tags exist or can be established within the source namespace.

A note about maxspeed (historic)

Note that source:maxspeed=* is frequently used to give information about the type of the speed limit. If you wish to tag both the type of the speed limit and also source information for how the information was collected then either use source:maxspeed=* in the way described on this page and use maxspeed:type=* for the type of speed limit (for example maxspeed=40, source:maxspeed=survey source:maxspeed:date=2012-11-20 and maxspeed:type=sign would indicate that a numeric sign showed a speed limit of 40 km/h based on a ground survey done on 20 November 2012, or use source:maxspeed=*. Please note that currently most usages of source:maxspeed=* are indicating the type of maxspeed, and that by the time this tag was introduced there were 0 occurrences of sources like documented here!

OpenHistoricalMap

Main article: OpenHistoricalMap/Good practice#Verifiability

Unlike OpenStreetMap, OpenHistoricalMap continues to tag source=* on individual features. In fact, you are generally expected to add source=* to each individual feature to avoid the appearance of plagiarism. It is not necessary to cite a built-in background imagery layer that you trace the geometry from, since that is already recorded in imagery_used=* on the changeset, but you should use source=* to provide a citation regarding start_date=*, end_date=*, and other attributes.

Specific values

General sources commonly used by human mappers

Value	Country(ies)	Meaning	Website	Note
survey	worldwide	The OSM user was there and saw it firsthand. The user may or may not have done any precision measurement of the location etc. using a device such as a GPS receiver.
extrapolation	worldwide	The information was extrapolated from other information in OpenStreetMap, but is still better than pure guesswork
GPS	worldwide	Someone measured the location using a GPS, GLONASS, Galileo, ATLAS or other satellite navigation receiver but did not copy the information from a map that might be installed in that receiver. Either the OSM user editing the object did this (and may or may not have uploaded a GPS track), or the OSM user downloaded one or more GPS track from the OpenStreetMap database (doing both is also possible).		(This was the default value in ancient versions of the JOSM editor)
mapillary	worldwide	Information was photographed and can be checked by everyone using a plugin for Mapillary photos. Mapillary is a service for sharing geotagged photos (open data alternative of Google Streetview). It is also possible to be more specific by pointing to a specific photo id (see mapillary=*)
image	worldwide	Information was photographed / video filmed (not from the air or space)		Indicate from which image it's from, or survey if you did take the pictures.
aerial_imagery	worldwide	General tracing of aerial imagery		Indicate from which imagery it's from, to make that verifiable and follow most sources' requirement of attribution.
common_knowledge	worldwide	The OSM user knows this from many informal source and believes it to be commonly known by most people who care. For instance most people know that the huge ocean between Europe, Africa and the Americas is called the Atlantic.		Prefer verifiable sources such as survey
local_knowledge	worldwide	The OSM user has some affiliation with the area (resident, place of work, frequent visits...) and knows this first hand or from others in the area		Prefer verifiable sources such as survey

Specific sources commonly used by human mappers

Tags used only by specific data import software

Usage statistics

For human mappers

source value	instances (change direction MM-YYYY of count)	meaning	short source	meaning contributor
Bing (and "bing")	>16.7 million ( Jun 2016)	Bing	Corporate (Microsoft)	Ceyockey
cuzk:km	>2.3 million ( Jun 2016)	Manual or semi-automatic tracing of Czech catastral map	Government (Czech Republic)	Ceyockey (see Tag:source=cuzk:km)
survey	>1.7 million ( Jun 2016)	See Key:source	OSM editor	Ceyockey

For import software

Possible tagging mistakes

See also

External links