No subject

advantages over BY-SA for geodata. Unlike the GNU GPL, BY-SA  doesn't
require the provision of source, and it may well be that geodata
source is more important for freedom of maps in general than copyleft
is for specific maps. BY-SA allows the creation of maps that cannot
usefully be used and modified because the original geodata that they
have been rendered from cannot be recovered from them. So in my
copyleft-proponent opinion it can be argued that ODbL protects access
to geodata more strongly *in practice* than BY-SA.

But I'm really feeling uncomfortable about the contract law component
of the licence...

- Rob.