Box Structures
 

Cleanroom depends on describing development with:
 

Black Box
A view of an object that hides data implementation and process implementation. It describes how a system responds to stimuli, usually in a formal specification language. Usually arranged into usage hierarchies.
 

State Box
A view of an object that shows data implementation but hides process implementation. It describes how "state" information is transformed.
 

Clear Box
A view of an object that shows both data implementation and process implementation. The goal is to stepwise refine procedures and to prove them correct.