In the general job shop model, there are a set of machines indexed by k. Jobs are indexed by i, and tasks are indexed by j.

Each task on a machine is indicated by a set of three indices, i, the job that the task belongs to, j, the number of the task itself, and k, the machine that this particular task needs to use.

The flow of the tasks in a job does not have to be unidirectional. Each job may also use a machine more than once.