Architecting and designing : IDEF : IDEF0 : Introduction to IDEF0
  
Introduction to IDEF0
IDEF0 is used to model the functions of the business or its systems. The result of applying IDEF0 is a model. The model consists of diagrams, texts, and glossary, cross-referenced to each other.
System Architect’s IDEF0 support includes the following:
Context diagrams
A context diagram is always the highest-level representation in the model and contains only one process. It is included in every IDEF0 model. IDEF0 modelers begin with the Context or A-0 diagram and then "drill down" into more detailed views of their enterprises. This diagram becomes the parent of the other IDEF0 diagrams.
Decomposition diagrams
After drawing the Context Diagram , you can view your enterprise in finer detail by creating (or attaching existing) Constraint diagrams. IDEF0 Constraint diagrams depict several subprocesses to describe the parent process: see Node tree diagrams.
Node tree diagrams
Once you have used the Child diagrams to decompose your enterprise to the level of detail you desire, you can build Node Tree Diagrams to view the hierarchical relationship among activities. Node Tree Diagrams are graphical representations of the processes and subprocesses of an IDEF0 model. Their tree format allows you to see your processes and subprocesses all at once.
See also
IDEF0