Compatibility between the GNU General Public License v3.0 or later (inbound licence) and the Apache License, Version 2.0 (outbound licence).

Compatibility is depending on the type of "Use".
- Private or internal use is never restricted by any open licence and the resulting combined work does not need specific licensing, as soon it is not distributed to third parties.
- In case the two components are not merged, but used according their normal usage instructions and distributed together to third parties (i.e. on the same media or distribution), each component - even modified - keeps its primary licence: inbound licence or outbound licence.
- In case the two components that could be used independently are linked for ensuring their interoperability, for example APIs or data structures for exchanging parameters are copied/reproduced from one program to the other,  Some legal theses (not confirmed in courts) state that by a kind of "viral effect" the inbound licence becomes applicable to the whole combined work. However, in so far the European Law would be applicable, it states that by exception to strict copyright rules, such reproduction can be done without obtaining the right holder permission or licence, provide this linking is compatible with a normal exploitation of the programs and does not conflict the legitimate interest of copyright holder. This is resulting from Directive 2009/24/EC recitals 10 and 15 invoking a copyright exception for making interoperable two components from various providers.
- In case substantial parts of the source code covered by the inbound licence have been merged / integrated with code covered by the outbound licence, the outbound licence, which is compatible with the inbound licence, authorise distribution of the whole combined work under the inbound licence. This is applicable to this new combined work only (a derivative or "forking" from both source codes, which is a specific project with a specific name), and does not normally authorises relicensing (changing the licence) of the original code covered by the outbound licence.