ATP Discrete vs Cumulative: Reading the Two Promise Columns in EDGEBIC

EDGEBIC by User Solutions shows available-to-promise in two columns: discrete ATP is the promise capacity at each supply point, the supply arriving there minus the firm demand up to the next supply event, while cumulative ATP is the running total carried forward across the horizon, so you read discrete to see where supply lands and cumulative to answer how much you can promise by when. Once you know which column answers which question, quoting a delivery date becomes a single scan down the cumulative column.

This post explains both columns, where the supply points come from, and how to turn the numbers into a promise. For the promise concept overall, see how available-to-promise answers a sales question, and for the wider loop start from the EDGEBIC planning guide.

Two Questions, Two Columns

Available-to-promise answers how much you can still commit to new orders without breaking the promises you have already made. EDGEBIC splits that into two columns because there are really two questions.

Discrete ATP asks: at this specific supply point, how much does the incoming supply free up on its own. Its value is the supply arriving at that point minus all the firm demand between it and the next supply point. It is a local number, tied to one supply event.

Cumulative ATP asks: through this point, what is the total I can still promise. It is the running sum of the discrete values, carried forward. It is a global number, the whole position up to a date.

You read discrete to understand where supply lands and how much each arrival contributes. You read cumulative to make an actual promise.

Where the Supply Points Are

Discrete ATP is not computed in every bucket. It is computed only at supply points, because those are the moments new promise capacity appears.

The first supply point is the current bucket, and it carries the real on-hand now, the true present stock. After that, every bucket with a scheduled receipt is a supply point: an incoming build-to-stock order due to complete brings new supply, so it opens a new promise position. Buckets with no incoming supply are not supply points. They have no new capacity to offer, so discrete ATP is blank there and the cumulative value simply carries forward unchanged.

This is why the discrete column looks sparse, populated only where supply lands, while the cumulative column is continuous, updating at each supply event and holding steady between them.

A Worked Example: On-Hand Plus One Receipt

Take a part with real on-hand of 120 and one incoming build-to-stock order for 150 completing in week 2. Firm demand is 50 in the week-1 to week-2 span, and 20 from week 2 onward.

There are two supply points: week 1, carrying the on-hand of 120, and week 2, carrying the receipt of 150.

At week 1: supply is 120, firm demand up to the next supply point (week 2) is 50. Discrete ATP is 120 minus 50, which is 70. Cumulative starts at 70.

At week 2: supply is 150, firm demand from here to the end of the horizon is 20. Discrete ATP is 150 minus 20, which is 130. Cumulative is 70 plus 130, which is 200.

Read the discrete column and you see the on-hand frees up 70 before week 2, and the week-2 receipt frees up another 130. Read the cumulative column and you see you can promise up to 200 total across the horizon.

Quoting a Delivery From the Columns

To promise a quantity, scan the cumulative column for the first bucket where it reaches your number. That bucket is the earliest date you can safely quote for that amount, because cumulative ATP is the total you can commit through that point without breaking existing promises.

Suppose a customer wants 180 units. Week-1 discrete ATP is only 70, so today's on-hand cannot cover it. But cumulative ATP reaches 200 by week 2, which is more than 180, so you can promise all 180 for a week-2 delivery. The discrete value told you where supply lands; the cumulative value told you the promise week 2 supports.

If no bucket in the horizon reaches your quantity, you cannot promise the full amount within the horizon on current supply. Then you either firm a replenishment to add a supply point, which lifts the cumulative column, or extend the promised date, or split the order.

When ATP Goes Negative

A discrete ATP can come out negative, and that is deliberate. A negative discrete value at a supply point means firm demand between that point and the next exceeds the supply arriving there, so at that point you are already committed beyond what lands. It does not block anything. It tells you where your promises run ahead of supply.

Watch the cumulative column to judge severity. If cumulative recovers at a later supply event, the local shortfall is covered downstream. If cumulative goes negative and stays there, you have over-promised across the whole horizon and need to add supply or move a commitment. Either way EDGEBIC surfaces the condition instead of hiding it, so you see exactly where and how far you are exposed.

Reading the Pair Together

The two columns work as a pair. Discrete shows the shape of your supply, where it lands and how much each arrival brings. Cumulative shows your promising power, the total you can commit through any date. Use discrete to understand the plan, and cumulative to answer a customer. When a promise does not fit, the columns also point at the fix: add a supply point and both climb.

For why negative promise numbers are information rather than errors, read why negative projected balance and ATP are information, and for the promise in a sales conversation, read how available-to-promise answers a sales question. For the concept in general terms, see what is available-to-promise.