Whose node is it?
Consider the case where:
- User A goes out and gathers a tracklog
- User B traces that to form a way
- User C tags it with "highway=primary"
- User D adds a name tag
- User E goes through and adds more intermediate nodes, so that it fits the tracklog better
- User F adds some shops and pubs as entirely separate nodes positioned relative to the road
How does attribution work for these parts of the map?
On the OpenStreetMap site we follow an attribution approach similar to Wikipedia. We have a history tab and various other ways of accessing the history of individual data elements, which gives access to a history display with links to the users who edited. Also as on wikipedia, we assume that data re-users can comply with the attribution requirement of the license by giving credit to "OpenStreetMap" rather than every individual contributor (which would make re-use impossible!) However we do recommend adding the words "and contributors" See the copyright & license recommendations.
However, as illustrated by the above scenario, OpenStreetMap data elements form a tangled web of inter-derived data. There are several types of contribution, not all of which are stored as explicit links in the data itself. We can't automatically present a display showing all the users involved in positioning those final shops and pubs, answering the question "Whose node is it?"
Why does it matter whose node it is? Generally it doesn't, but we have some situations where users are attempting to license their copyrighted contributions differently from the rest of us. 'The rest of us' can be assumed to be releasing data just with the OpenStreetMap License (currently CC-BY-SA, with a plan to move to ODbL). But what if user B wants to...
- ...dual-license her contributions, making them available also to the Public Domain
- ...remain with the old CC-BY-SA license while the rest of us are trying to move to the ODbL
These are open issues although they have been extensively discussed in relation to Open Data License FAQ#What happens if not everyone agrees?