Definicja firm/trade-off zone

A time zone of a delivery schedule defined in a scheduling agreement consisting of two sub-zones that determine the degree to which individual lines of the schedule represent binding orders, or commitments to purchase.

There is a firm zone (indicating firm commitments) and a trade-off zone (indicating semi-firm commitments). Both are specified in days.

Example

If the firm zone amounts to 20 days, all schedule lines whose delivery dates do not lie more than 20 calendar days in the future (calculated from the current date) are regarded as "firm" (that is to say, they count as fully binding purchase commitments).