[officialchicken]

RTFM/from the article...

>CERN ended up with three variants. There is a strong reciprocal licence (CERN-OHL-S), which is for designs that remain free along with all their derivatives, a copyleft principle similar to GPL.

>There is a weak reciprocal licence where the design can be used as a component in other designs without the whole becoming open source, but if the design of the component is modified, that must be shared back (CERN-OHL-W). And there is a permissive licence, CERN-OHL-P, which lets users mix the design freely with proprietary designs provided it is acknowledged, similar to Apache 2.0 in the software world.