Adding a permissive license under such a similar name worries me. People are often fairly lax about reading the details in licenses. I can imagine someone licensing under CERN-OHL-S, and someone else finding the CERN-OHL-P guidance.
- GPL and LGPL look far more different than CERN-OHL-S and CERN-OHL-L
- GPL and MIT even more so, whereas CERN-OHL-S and CERN-OHL-P again look so similar.
I know creative commons have lots of licences too, but I have met no end of people who either just say it is CC, or who are confused about what each thing means. Perhaps CERN-OHL, CERN-LOHL and CERN-POHL seems somewhat clearer?