OpenHistoricalMap/Copyright
OpenHistoricalMap strives to dedicate as much of its contents as possible to the public domain under a Creative Commons CC0 dedication, which means there are as few restrictions as legally possible.
Contributing data
By default, your contributions to OpenHistoricalMap are presumed to be dedicated to the public domain unless otherwise noted. This means any external source you copy from should also be in the public domain if possible.
Since individual raw facts are ineligible for copyright protection, you are free to glean them from any source, regardless of copyright status, license, or medium. This includes books, newspaper articles, telephone directories, and webpages. However, you should exercise more care around copyrighted maps, because the specific graphical depiction of a geographical feature may be subject to copyright protection. Out-of-copyright maps are of course perfectly acceptable. Some elements distinguish between different reasons for the lack of copyright protection via tags such as license=CC0-1.0 or license=copyright expired.
You should also respect any applicable database rights. Avoid the wholesale substantial copying of data from copyrighted datasets published in jurisdictions where database rights are legally recognized, such as the European Union. This includes OpenStreetMap data.
As a contributor, you have the option to indicate that a specific element is copyrighted but available under an open license, such as Creative Commons Attribution 4.0. To do so, set the element's license=* tag to an SPDX license identifier such as CC-BY-4.0. If the license requires attribution, set the element's attribution=* tag and also insert the required attribution into OHM's centralized acknowledgment of sources. Note that we no longer accept contributions of "no derivatives" or "non-commercial only" licenses.
We encourage you to stick to public domain content whenever possible, only opting for this per-element licensing when no alternative sources of information are available. Please be aware that, in the future, we may decide as a project to phase out copyrighted content, which would entail the deletion and possible replacement of copyright-encumbered material.
Rationale
OpenHistoricalMap has deliberately avoided placing the entire database under a viral copyright license or database license for several reasons. The field of historical geography differs significantly from the more consumer-oriented space that OSM inhabits. As an unconventional GIS dataset, OHM does not have to worry very much about being co-opted by well-resourced companies seeking a competitive advantage for their proprietary datasets. Instead, we compete against many overlapping academic projects, differentiating ourselves by our emphasis on collaboration and reuse. The field is dominated by noncommercial educational institutions that enjoy significant fair use protection, which means they are not necessarily bound by any share-alike provisions anyways. These same institutions are major potential sources of data, expecting citations that we can provide alongside the database. Moreover, OHM is based in the United States, where compilations of facts do not enjoy significant legal protection. Fortunately, academic standards against plagiarism already strongly encourage attribution – even acknowledgment of intangible contributions that a copyright license can never enforce.
OpenStreetMap
Unlike OpenHistoricalMap, OpenStreetMap has adopted the Open Database License, which comes with a number of requirements related to copyright and database rights, as well as Community Guidelines that attempt to clarify this license for various use cases. Therefore, you may freely use OHM data inside OSM or any other project, whereas the reverse is not necessarily true. Depending on authorship, you may be able to transfer some features from OSM to OHM without involving licensing considerations.
Further reading
- Welty, Richard (August 4, 2020). “moving OSM data to OHM - dealing with the license”. OpenHistoricalMap.