For those interested the others are:
OEM:SLP = System Locked Pre-installation key - Win Vista/7 manufacturer specific keys used to mass activate those installations. Activation is offline with a SLIC table in the firmware and matching Certificate installed together with the key.
OEM:COA = Certficate of Authenticity key found as a sticker attached to PC's factory installed with the above OEM:SLP method as a backup for online re-activation.
OEM:NONSLP = Non-System Locked Pre-installation key a.k.a System Builder keys - available from re-sellers and acts as retail online activation keys but with an OEM EULA.
Tried to run ShowKey Plus but my AV sw blocks the code as being unsafe to run ......
Thanks to both of you, will run it anyway ...
Unfortunately, since I included the version updater that checks GitHub for newer versions, it sees it as PUP... should I exclude the auto-check and rather have a link to check?
A warning on 1st run/install should be fine. I think using the latest version is important