CUA originated on terminals, specifically it was made to unify different approaches used across block terminals, character terminals, DOS apps, and early PC GUI

CUA originated on terminals, specifically it was made to unify different approaches used across block terminals, character terminals, DOS apps, and early PC GUI apps. It's also explicitly a Human Interface Guideline, whereas ANSI terminal standards are just interoperability instructions on how to drive a character terminal and declare nothing about how to actually use them for application UI.