every single order must be planned backwards starting prom a point zero (the point after which it is no longer necessary to have processes monitored because there is a minimum risk of jamming). choosing a reference time unit called setsuban (can be days, weeks, decades or months), a number of time units are accounted for in the calendar and the duration of each stage in the working flow is fixed accordingly, and referred to by using delivery indicators called "teban" (see below).