You do not accept that your software could be "appropriated" by third parties: copies and derivatives must stay distributed to all under "free / open source" conditions. This is the concept of "reciprocal" (or "share alike" or "copyleft") licences, which - in case of redistribution of copies or derivatives by third parties, imposes to provide back the source code under the same licensing terms, or - in some cases, under compatible licensing terms.
Which reciprocal licence would you prefer?
- Would you prefer a licence based on European law and terminology, with legal value in all EU languages?
- Would you prioritise a licence (official value in English) that is more emblematic of the "free software philosophy" and focused to a worldwide propagation?