11.6 Chapter 1 asked you to construct a physical DFD of the LozCo system.

LozCo keep machine maintenance records that they update as shown below. Construct an entity life history (ELH) of the machine maintenance record from the description below.

When a new machine is installed in the machine shop LozCo create a machine maintenance record. This is used to hold a running total of the product produced by the machine. The machine is reserved for the manufacture of a particular group of products, and this is recorded on the maintenance record card.
When the machine is installed, it is passed for service by a quality inspector, who checks that the commissioning and installation have been done correctly. The equipment manufacturers employ these inspectors, and details of inspections are recorded on the maintenance record. If a machine fails this quality check then the check is repeated later until the standard has been reached. The total quantity produced per week is accumulated in the maintenance record, and this figure is incremented each week.
Routine maintenance is conducted twice a year at roughly six-month intervals. The equipment manufacturer’s staff undertake the maintenance, and details of the most recent maintenance are held on the record. When a machine is removed from service at the company it is either scrapped or sold second-hand, and its date of removal from service is recorded. The accounts department records any costs or income derived from its disposal at the end of the year.