IPO chart is a method for describing a  ?????

????? chart consists of three columns with the headings input, process and output.

????? charts use top-down design.

Processes are refined into subprocesses or  ?????.

Hierarchy chart passes control from the  ????? level down to the first refinement.

Procedures are  ????? that specify what processing is to be performed.

Resources are  used by the  ????? to perform the task.

A  ????? is a system whose internal parts are not fully understood.

The  ????? is the elements outside the system that affect the system.

The  ????? separates a system and its environment.