2.3 Product flow diagram
If you have adopted a product-driven approach, it is possible to draw up a product flow diagram (PFD) showing the order in which products have to be created. This should be relatively easy to draft if you have already produced product descriptions that specify from which other products each product is derived. Figure 2.2 gives an example fragment of a product flow diagram.
Fig. 2.2 A product flow diagram
Note the oval with ‘software specification’ in it. This refers to a product that already exists and that will be used to generate one or more of the products in the PFD.
There is no one correct PFD — its structure depends ...