WaveSurfer is free software, distributed under a permissive free software licence.
The Ruby License is the free software licence applied to the Ruby programming language and also available to be used in other projects.
"This is a free software licence, compatible with the GPL via an explicit dual-licensing clause."
It is a free software licence.
Both sets of free software licences offer the same freedoms in terms of how the software can be used, studied, and privately modified.
Some permissive free software licences contain clauses that make them incompatible with copyleft licences.
However such restrictions also make the licence incompatible with permissive free software licences.
"Patent retaliation" clauses are included in several free software licences.
Copyleft licences are free content or free software licences with a share-alike condition.
The first licence wasn't a free or open-source software licence.
