Order – an order in this context is an ordered sequence of one or more operations that is required to be performed to produce some part, product or service.
Job – synonym for order that is often used in scheduling literature
Operation – an operation is an individual activity or task that must be performed to fulfill an order. The operation must be performed by a specified resource or a set of alternate resources and requires a specified set of raw materials and/or sub-parts.
Operation setup time – the preparation time needed before an operation can start.
Operation run time – the time it takes to perform the operation.
Release date – the earliest date the first operation of the order can start.
Due date – the date when the order is planned to be finished.
Order start and Order end – the current start and end of the order when it is in process.
Lead time – the total time it takes to execute an order and is the time from the first operation is started to the last operation is finished.
Order slack – The sum of all setup and run times for all remaining operations subtracted from the time remaining to the due date
Lateness – the difference between an order’s due date and the actual end date of its last operation. Lateness can be positive or negative, positive if the end date is after due date and negative if end date is before due date.
Tardiness – a tardy order is one who’s last operations end date is after its due date. Tardiness is the same as positive lateness.
Forward scheduling – operations of an order are scheduled as early as possible starting from the release date.
Backward scheduling – operations of an order are scheduled as late as possible backwards from the due date
Static scheduling – the scheduling is performed on a fixed set of orders. This is the type of scheduling considered in this dissertation and also in much of the literature on scheduling. It can be viewed as scheduling a snapshot of a production environment.
Dynamic scheduling – new orders are continuously added during scheduling.
Production resources – personnel and/or machines that performs production in a company.
Work center – a production area consisting of production resources with similar capabilities.
Shift – a time interval describing when production resources are available.
