Just to add a link to my collection of the (IMHO) most relevant statements about OpenPOWER:

https://morph.zone/modules/newbb_plus/viewtopic.php?topic_id=7183&forum=3&start=897

> IBM Opens Up POWER Architecture For Licensing

That article is bad btw, as it confuses Power Architecture, which is an instruction set architecture (ISA), with IBM POWER, which is one of many microarchitectures implementing said ISA. OpenPOWER is specifically about IBM POWER, not about any other of IBM's Power Architecture implementations or even Power Architecture in general.