OpenHistoricalMap/Tags/Key/license
 license
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Indicates the data license associated with the feature. 
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| Group: annotations |
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| Status: de facto |
| Tools for this tag |
This key identifies the license of an individual feature in OpenHistoricalMap. Some features have been contributed under a different license than the database as a whole, which may require extra care on the part of data consumers. Any feature without this key is presumed to be in the public domain through the project's public domain dedication.
History
Historically, OpenHistoricalMap did not adopt a uniform license for the database and its contents. Instead, individual mappers contributed individual features under disparate licenses of their choosing. This led to confusion about how OHM data could be used while satisfying these licenses, not to mention difficult questions about how features under incompatible licenses could coexist within the same database.
On August 3, 2022, OpenHistoricalMap adopted Creative Commons Zero (CC0), dedicating the database to the public domain to the extent possible, unless otherwise specified by a license=* tag. [1] It remains possible to contribute data under copyright, but the project now strongly encourages releasing new contributions into the public domain.
In February 2023, an import of bus stops in Belgium came with licence=* tags, making that spelling 25% more popular than license=*. However, in January 2024, the Newberry Library Atlas of Historical County Boundaries import included license=* tags, making this spelling 155 times more popular. [2]
How to map
OpenHistoricalMap strongly prefers that you omit this key from any original contributions of yours, in order to release them into the public domain. This facilitates the database's reuse and the sharing of knowledge about not only what you are mapping but also everything connected to it in some respect.
That said, if you must introduce third-party data that is encumbered by a copyright or database license, add license=* to each element that has any other tag on it. It is presumed that a way's license=* tag also applies to untagged nodes along the way, and that a relation's license=* tag also applies to untagged ways that are members of the relation, as these untagged features only exist for the purpose of defining the tagged feature's geometry.
Use an SPDX identifier if possible. Most common licenses are registered with the Software Package Data Exchange, which is part of ISO/IEC 5962.
Acceptable values currently include, in order of preference:
- CC0-1.0 – Creative Commons CC0 v1.0 Universal
- CC-PDM-1.0 – Creative Commons Public Domain Mark 1.0 Universal
- DL-DE-ZERO-2.0 – Data licence Germany – zero – version 2.0
- CC-BY-4.0 – Creative Commons Attribution 4.0 International
- DL-DE-BY-2.0 – Data licence Germany – attribution – version 2.0
- OGL-UK-3.0 – Open Government Licence v3.0
- CC-BY-SA-4.0 – Creative Commons Attribution Share Alike 4.0 International (provisionally, under the assumption that the OHM database is a collective work)
- ODbL-1.0 – Open Data Commons Open Database License v1.0 (but you must avoid substantial reuse of the original data source)
This list is subject to change. If you would like to import data that is under a license that is not listed here, please start a discussion about it on the forum. The community also reserves the right to phase out any non–public domain licenses in the future, as it becomes feasible to do so, in order to provide more clarity and legal reassurance to both mappers and data consumers.
Common values
As of April 2024, 63% of explicitly tagged features were licensed under CC0-1.0, CC0 / public domain, or CC0, which simply reaffirms the project's decision to use a public domain dedication by default. Some other values, such as public domain and copyright expired, bring the share of public domain data to 84% of all explicitly tagged features. The next most common licenses are the ODbL at 10%, Creative Commons Attribution at 2%, and Creative Commons Attribution–ShareAlike at 1%. (The ODbL generally identifies data imported from OpenStreetMap.) No other license reaches one percent of license=* usage.
Note that these statistics are limited to features with explicit license=* tags, which are only 0.12% of all features in OpenHistoricalMap.
See also
External links
- Discussion and poll to unify license=* and licence=*