Computing item ATP

The available-to-promise (ATP) is calculated for items with supply in order horizon or master horizon.

The order horizon ATP is based on the demand and supply in the ATP field of the Item Order Plan (cprrp0520m000) session.

In the Item Master Plan (cprmp2101m000) session, several fields give an indication of the item quantity that is still available at a certain point in time:

  • Projected Inventory
  • ATP
  • Cumulative ATP

The projected inventory shows the inventory level as it is expected on the basis of the previous inventory, the expected demand, and the planned supply. For more information, refer to To compute the projected inventory

The available to promise (ATP) is an indicator of inventory availability that is specifically geared to the process of order acceptance. In the Item Master Plan (cprmp2101m000) session, the ATP is shown in two formats:

  • The ATP for one plan period
  • The cumulative ATP

  • Computing the ATP for one plan period

    The ATP for one plan period is a value of zero or higher, which indicates how much of the planned supply for a plan period is not already used to cover actual demand.

    The total planned supply for a plan period is displayed in the Total Receipts field in the Item Master Plan (cprmp2101m000) session, and is equal to the sum of the:

    The total actual demand is equal to the sum of:

    For the current plan period and each subsequent period within the ATP/CTP horizon, the ATP is computed as follows:

    • For the current plan period,

      The on-hand inventory is added to the ATP

    • If the result of the ATP computation is negative

      The ATP for that plan period is set to zero.

    • Part of the item's ATP within a plan period is reserved as a so-called component CTP reservation

      This CTP reservation is subtracted from the ATP of the (component) item. See Component CTP reservations.

  • CTP reservations

    If component and/or capacity CTP checks are enabled for a plan item, this influences the way in which LN deals with negative ATP levels when it updates the ATP.

    If the cumulative ATP of such a plan item becomes negative, the negative ATP level is passed on to:

    • The item's CTP-critical components, as a component CTP reservation.
    • The item's CTP-critical resources, as a capacity CTP reservation.

    In this case, the additionally produced quantity of the item itself is stored as CTP reservation receipts.

    CTP reservations are subtracted from a component item's ATP or a resource's capacity CTP. This means that an item's ATP is lowered by any component CTP reservations made for that item by higher-level items in the bill of material (BOM).

  • Order promising

    Cumulative ATP is a convenient tool for order promising. When it comes to accepting customer orders, a plan period's cumulative ATP is a clear indicator of the order quantity that you can still promise to deliver in that plan period.

    Usually, when reference is made to checking an item's ATP (in a general sense), what is actually checked is not the ATP as you can find it in the Item Master Plan (cprmp2101m000) session, but rather the cumulative ATP.

    The functionality behind the notion of cumulative ATP is further enhanced by extended capable-to-promise (CTP) checking techniques. These techniques do not only consider what can be promised based on the planned supply, but also explore the possibility of producing more than the current supply planning indicates.

  • Channels

    In the Channel Master Plan (cpdsp5130m000) session, channel ATP is used. Channel ATP does not depend on item availability, like item ATP, but is derived from the allowed demand for the channel in question.