Draw DFDs for each of these scenarios:

(a) A customer goes into a bookshop and asks for this book. The member of staff looks for the book in the online stock catalogue and reports that the book is sold out.

(b) Every month, the Medical Centre receives a list of current drugs available from the drug companies. These lists are collated into a catalogue of drugs which is copied and given to each doctor.

(c) Swillbuckets orders a crate of Babycham from the brewery. Jack Trout fills in an order form and sends copies to the brewery and the barman. The original is kept in the Orders shoebox. When the order arrives, the delivery note is checked against the order form by the barman. If the delivery matches the order, the barman signs the delivery note and attaches it to the order. He sends this to Jack.

(d) Decompose the diagram for part (c) into two lower level DFDs, one showing the order process and one showing the delivery process. Compare them with the top-level DFD in (c).