[odc-discuss] offering adapted versions

[Anthony]

Hi all,

As I'm sure you're all aware, the OpenStreetMap Foundation is
switching its license from CC-BY-SA to ODbL/DbCL.  I have a few
questions about how the ODbL works.  Unfortunately my questions might
not make sense to those not familiar with the technical workings of
OpenStreetMap, at least with regard to tiles (and, really, Mapnik),
but I figured I'd take a stab on this mailing list.

"If you publicly use any adapted version of this database, or works
produced from an adapted database, you must also offer that adapted
database under the ODbL." - that's from the plain English summary of
the ODbL.

How long do I have to keep a copy of the adapted database in case
someone takes me up on my offer?  How much of the database do I need
to keep?  Is the offer valid to third parties?  If person A makes a
bunch of tiles from a database, and person B prints out a map from
those tiles and gives the map to person C, who offers person C the
copy of the adapted database?  (Person B likely doesn't have a copy,
but Person A would have to keep a ton of obsolete data indefinitely if
his offer is valid to third parties.)

As of right now I have produced hundreds of thousands of tiles from a
myriad of different versions of a myriad of different databases.  If
someone asked me to give them a copy of the adapted database, I
couldn't possibly comply.

Are there any suggestions as to how (technically) to keep track of
this in order to remain compliant?  I'm especially stumped on how to
handle the three party scenario, both as person A and/or as person B.
(And of course all the even more complicated versions of it, like a
database being used to make tiles, which are used to create a video,
which is used in a television broadcast, which is recorded to a DVD,
which is sold in a store...)

Thanks in advance,
Anthony