documenting licensing

[andrewharvey]

It's the job of ELI to:

• Only accept imagery which can be used for tracing into OSM
• Maintain some kind of documentation of (1) so if someone later claims why are you using this imagery for tracing in OSM we can back that up with documentation from here.

(up until today) we had a few fields for recording licensing:

• license license of the imagery using SPDX id or "COMMERCIAL"
• permission_osm enum of explicit, implicit, no
• license_url URL for the license OR permissions for the imagery

I'm proposing an alternative:

• license - The name of the license the imagery is generally made available under. If the license has an SPDX identifier, we prefer to use that. If it's a non-standard license you may omit this.
• license_url - The URL of the license the imagery is generally made available under. If it's an SPDX license you may omit this.
• waiver_url For sources that require an additional waiver or explicit permission to use in OSM beyond the license, the URL to the waiver should be present.

At a minimum you have to supply at least one of these fields.

[simonpoole]

At the time I introduced license it was to be able to determine if a source can be used freely outside of the narrow context of use for editing OSM.

The obvious (hypothetical at this point) use case is creating a (global) mosaic of free aerial imagery sources, which while it wouldn't be perfect, these days it could have significant hi-res coverage. Even if the project is less ambitious than that it would still be useful to quickly determine if there is a freely usable source for a certain area. Given that it is something that a contributor to this repo already has had to find out, it would seem to be reasonable to maintain that information here, instead of forcing this to be redone time and time again and it is very unfortunate that the work already done was thrown away on a whim.

Anyway back to your suggestion, there are three cases that I can see

1. imagery that is licensed on commercial terms, waiver_url (perhaps permission_url would be more generic) in general the commercial terms are not something we are interested in so no need to link to those, the absence of the other fields would need to imply a commercial / non-open licence.
2. imagery that is licensed on open terms that however require a waiver for use in OSM, license needs to be set to the SPDX value, waiver_url needs to present (this could actually be validated).
3. imagery that is licensed on open terms that are compatible with OSM, license needs to be set to the SPDX value, and imho license_urlshould be pointing to the location the license for the source is stated (not the license text, as we want to be able to verify that the license is actually the correct one for the source).