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ATP with Backward Consumption and Accumulation, Accumulation Window of 2 Days

Periods 1 2 3 4 5 6 7 8
Total Supply 6 4 2 4 8 4 4 4
Total Demand 6 2 3 6 6 1 2 2
Projected QOH 0 2 1 (-1) 1 4 6 8
Period ATP 6-6 4-2=2 2-3= -1 4-6= -2 8-6=2 4-1=3 4-2=2 4-2=2
Accumulate, 2 Day Window   2-> 2-1=1   2-> 2+3=5 3-> 3+2=5 2-> 2+2=4
ATP 0 1 1 -2 2 5 5 4
New Demand           5  
New ATP 0 1 1 -2 2 0 0 2

Table 1 - 25. ATP Periods, Backward with Accumulation, 2 day Window rule (Page 1 of 1)

With this rule, demand is subtracted from supply within each period, and the remaining quantity available is carried over into the next period. Negative quantities are not carried over (accumulated) to future periods. However, accumulating quantity is limited to two days. Beyond the accumulation window, the quantity is no longer available. This accumulation window is also used for backward consumption; ATP goes back no further than the accumulation window in doing backward consumption.

In the example, accumulation begins with the excess supply out of period 2. It carries over into period 3, where demand exceeds supply by 1. The remaining unit does not, however, accumulate from period 2 into period 4, as the end of the accumulation window has been reached. Period 4 has negative ATP as demand exceeds supply, and period 3, the only period within the accumulation window of period 4, has no excess supply. The accumulation window comes into play again in period 8. Here, ATP is 4, consisting of the 2 available from excess supply within the period, and 2 carried over from period 7. The 3 in period 6 reaches the end of the window, and so is not included as available to promise in period 8.

ATP check for a new order: the largest ATP is 5 in period 7. We can enter an order for 5 to ship in period 7. For a subsequent ATP check, ATP for period 7 becomes zero, as is ATP for period 6. ATP for period 6 goes to zero as the period 7 order for 5 backward consumes 3 from period 6 and the remaining 2 in period 7.

See Also

ATP with No Backward/Forward Consumption, No Accumulation (Period ATP)

ATP with Backward Consumption

ATP with Backward Consumption and Accumulation

ATP with Forward Consumption

Defining ATP Rules

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