CUA = Common User Access
It was a set of recomendation from IBM to develop UI written in the late 80s. It was originally targeted to character-based UI, but later IBM delivered a winform version (mainly for OS/2).
The
Work With Pattern was a key component of the CUA.
It's no longer active.
See
Common User Access-A consistent and usable human-computer interface for the SAA environments for an intro on the subject.