You can model both Level 1 and Lower Level data flow diagrams (DFDs).

The DFD diagram uses the concept of leveling, where a given process symbol can be “decomposed” or “exploded” into its components at a lower level. The process symbol on the higher level represents all the functionality depicted in the decomposition diagram at the lower level, sometimes referred to as the “child diagram.”

This procedure enables the modeling of extremely complex designs in diagrams that can be comprehended by the average person; that is, a DFD is limited to “7 plus-or-minus 2 process symbols,” the traditional concept of the number that anyone can understand at one time. Note, however, there is no intrinsic limitation in System Architect to a maximum of 9 processes on one diagram.