Compatibility of Liberal Licenses
Compatibility with each other and with other licenses
Umrella licensing is another concept introduced with the Liberal Licenses to provide the best possible compatibility. Umbrella licensing means you license a larger work as a whole on top of the licenses already given for parts of that larger work, in order to enable your licensees to handle your larger work under a single license, in addition to the existing licenses for its parts.
Altered or changed material under a Liberal License is always licensed under the same Liberal License, no matter if included in a larger work, but in case of a larger work the licensee who becomes licensor of that larger work is allowed to apply in addition an umbrella license to the larger work as a whole, if that particular umbrella license is admitted by the respective Liberal License. This means that somebody who receives a larger work containing a material that has been licensed before under a Liberal License, must receive with that larger work at least two license agreement offers: the offer for the license used for the larger work and as well an offer for the original Liberal License used for the respective licensed part.
Therefore the umbrella licensing is effectively a kind of dual-licensing or multi-licensing. The licensee can choose to which license agreement he wishes to agree, or to agree to both, depending on what he plans to do. To use a licensed material as a part of a larger work he has to agree to the umbrella license, but to use a material licensed under a Liberal License which is part of a larger work isolated from the rest of the larger work the licensee may choose to agree to the original Liberal License of that part only or in addition.
Imagine the following case: Person A creates a software library under a LL-AS and Person B uses that library in his own application project (larger work). Person B chooses to license his application with a LL-PS. Now, the LL-PS is the umbrella license, but the LL-AS is still active for the library. Person C receives the application from Person B together with two licenses: the LL-PS for the application and the LL-AS for the library. If Person C wants to use the application he must agree to the LL-PS. Now, Person C wants to decompile the library from Person A that he got included in the application from Person B, but that is not allowed under the LL-PS. Fortunately he can agree to the LL-AS license agreement of the library. The LL-AS allows him to decompile the library (but not the other parts of the application).
The umrella licensing adds a great compatibility without adding restrictions for the licensees and without creating a loop hole in the regulations which protect the interests of the licensor.