While the meta key is well documented, the meh key is vaguely mentioned in multiple modern split keyboards such as ZSA keyboards and the Kinesis Advantage.

I’m seeing super, hyper, and meta on the Space-Cadet, but no meh.

Thanks for the reply! That would be good info to include in the future wiki. Still curious if this key originated with some 1970s era keyboard or if it came from something more modern.