Each line-item consists of a part number, the quantity ordered of the part, the cost of the part, and a description of the part. Line-items can involve use of many different machines in the shop, each with different hourly rates. Each line- item involves several tasks. Thus, tasks are primarily characterized by which machines on the shop floor must be utilized to complete a typical line-item. Employees are assigned to perform tasks on line-items of an order based on the areas in which they are skilled.
Employees can work on the tasks of more than one line-item and more than one order.
The tasks of a particular line-item may be assigned to several different employees, although most tasks must be done sequentially. Note that Carl's company may make the same part for several different companies. There are many different machines in the shop such as lathes, mills, and welders, each with different hourly rates. The database must keep track of the total time spent using each machine for each line-item of an order. This information is used for billing, for proposing estimates for future orders, and as an audit trail to determine employee productivity.