[cjh_]

Not quite, the 'Model M' actually refers to a collection of keyboards, some of which used rubber domes (see column 2 of [1] for a quick reference)

[1]https://en.wikipedia.org/wiki/Model_M#Features_by_part_numbe...

[nitrogen]

Interesting. I have a few IBM non-buckling-spring keyboards, but didn't realize they might also fall under the "Model M" designation.

[chiph]

They're like the Klingons from TOS -- we just don't talk about them.