Three data-centric, overlapping views

The three views are cross-validating, helping to identify gaps / inconsistencies early. Spotting them early is key to a successful project - the later they are found, the more costly and the more hassle it will be to sort out.

For example, while doing some LDM'ing with the users, someone mentions off-handedly that the best customers get a seasonal gift pack, depending on volume of orders placed... Whoa! There's a whole bunch of processes missed on the DFD - setting the volume(s) that defines a 'best' customer, providing names and addresses of customers meeting the criteria, mailmerging to produce greetings cards, etc.

While CRUD'ing you might find an entity never has a creation or, more likely, a deletion event. Is there a missing process on the DFDs? Was an event not spotted on the DFDs / during function definition, when preparing the CRUD Matrix?