| Component CTP reservations |  |
| ERP LN calculates CTP reservations when a plan item's ATP is updated, or when an item master plan is updated. Component CTP reservation ERP LN generates a component CTP reservation in the following situation: The cumulative ATP of a plan item in a particular plan period becomes negative. You selected the Component CTP check box in the Items - Planning (cprpd1100m000) session for the plan item involved. You selected the Critical in CTP check box in the Items - Planning (cprpd1100m000) session for (one or more) component items of the plan item. You entered a sales order, and the cumulative ATP of the end item and/or the cumulative ATP of one or more components is not enough. Note When component CTP reservations and/or capacity CTP reservations are made for a plan item, the expected additionally produced quantity of the item itself is stored as CTP reservation receipts. Calculation The component CTP reservation is computed as follows:
    CCR(t) = -NA(t) x	 RQ(t)
CCR(t) | component CTP reservation
NA(t) | negative ATP
RQ(t) | required quantity
The requirement date for the component CTP reservation for a critical material is determined as follows:
    RD = PFD - LTO
RD | requirement date for the component CTP reservation
PFD | finish date of the originating plan period
LTO | lead-time offset
ERP LN converts the lead-time offset from workdays to calendar days. See Workdays and calendar days in Enterprise Planning. ERP LN records the component CTP reservation in the plan period in which the requirement date falls. The component CTP reservations are subtracted from the (component) item's ATP. You can view component CTP reservations and their origin in the CTP Reservations (cprrp0111m000) session. This session is accessible through the appropriate menu of the Item Master Plan (cprmp2101m000) session. Related topics Types of ATP and CTP checks Component CTP To compute item ATP CTP Checking Procedure Capacity CTP reservations To compute cumulative ATP |