ATP with Backward Consumption (Oracle Inventory Help)


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ATP with Backward Consumption

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	1	2	2
Backward Consume Period 3		2-1=1	<- -1	-2+1
Backward Consume Period 4		1-1= 0	<--	<- -1
ATP	0	0	0	-1	2	3	2	2
New Demand						3
New ATP	0	0	0	-1	2	0		2

With the backward rule, demand is subtracted from supply within each period, as long as sufficient supply is available. If supply is insufficient to meet demand in a period, ATP checks prior periods, and matches excess demand to excess supply from a prior period. This is illustrated in period 3, where demand exceeds supply by 1. ATP uses supply from period 2 to meet excess requirement in period 3. In period 4, demand again exceeds supply, so ATP goes back to period 2 again and uses the last remaining supply. Period 4 is still short 1. ATP checks prior periods up to the ATP run date, searching for a quantity available to use for period 4. As long as no prior periods with available supply exist, ATP for period 4 is -1.

ATP check for a new order, quantity of 3 in period 7: ATP shows insufficient quantity to promise to meet this demand for the requested date. Instead, ATP returns an earliest ATP date of period 6. We can place new demand for period 6. After placing this new demand, ATP for period 6 shows zero.

Note that the ATP check showed the projected quantity on hand for period 7 is more than enough to meet demand. But this quantity comes from a build-up from prior periods. The ATP rule says not to accumulate available quantities. ATP for period 7 is period 7 supply less period 7 demand, giving an available to promise of 2.

ATP with Backward Consumption

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