> Is this the same Rational as Rational ClearCase etc as acquired by IBM back in the day? Crazy

Looks like it:

https://en.wikipedia.org/wiki/Rational_Software

> Rational Machines is an enterprise founded by Paul Levy and Mike Devlin in 1981 to provide tools to expand the use of modern software engineering practices, particularly explicit modular architecture and iterative development. It changed its name in 1994 to Rational Software, and was sold for US$2.1 billion (equivalent to current US$3.59 billion[1]) to IBM on February 21,[2] 2003.