См.: буферные области.
buffer regionsbuffer regions - -The buffer (time, stock, etc.) is divided into separate segments to indicate the need for proactive action to prevent lateness of a part/product/person or starvation of a constraint. The regions are typically called the red, yellow, and green regions and are generally 1/3 of the total buffer size each although the relative size may differ dependent on the specific characteristics of the process flow and product. Sometimes the term white region is used to refer to orders that have been released early (ahead of schedule) and the term black region is used to refer to late orders. The top figure illustrates stock buffer regions and the bottom figure illustrates time buffer regions.
Illustration 1: The regions of a stock buffer for a part or product.
Illustration 2: A time buffer for an order.