Reading MRP Action Messages: What to Do, and in What Order

MRP action messages turn a plan into a worklist: one thing to do, about one item, on one date. A time-phased calendar states a position for every part in the plant. It does not say what to do about it, and no planner should have to read every row of every item to find the dozen that need a decision this morning. In EDGEBIC by User Solutions, the MRP Worklist does that filtering, and two rules about what it refuses to say are what make it trustworthy.

This post covers the nine message types, the order to work them in, and the two deliberate silences. It sits under the EDGEBIC planning guide and follows low-level codes and why every item is planned exactly once.

The Nine Messages

Nine types is not many, and that is intentional. Each one corresponds to a single physical action a planner or buyer can take today.

The Order Is Part of the Message

The worklist arrives sorted by urgency, and the top of it is not simply "the biggest shortages."

Two message types outrank everything, because they are statements about the plan rather than about an item. A cyclic bill of materials means that product has no plan at all, so nothing else the run says about it can be judged. A horizon truncated message means demand or supply fell outside the window, so the figures describe the window rather than the plant.

Truncation deserves particular respect because it is contagious downwards. A parent whose demand fell off the end of the horizon plans no order, so it explodes nothing, so every component beneath it reports a comfortable balance it has not earned. One truncated item at the top can make an entire level below it look idle. Widen the window and rerun before working anything else.

After those two, the practical order is: past-due releases, then releases inside the window, then expedites and overdue receipts, then past-due demand. Defer and cancel are tidying: they free cash and space without costing service, so they can wait for a quieter afternoon.

A Message That Cannot Name Something Is Not Generated

This is the rule that decides what the list is worth.

Reschedule-out and cancel both name the order to move: defer that purchase order, cancel that manufacturing order. That precision is possible only because the plan carries incoming receipts by identity, with their reference and their date, rather than as anonymous bucket totals. Holding totals only, the most those messages could honestly say is that some supply somewhere may be early, and a worklist full of messages naming nothing is worse than a shorter one that names something.

The same principle shapes the Expedite message. It is generated once per item, not once per breached bucket, because the action is the same phone call however many buckets are affected. Three messages saying the same thing is noise dressed as thoroughness.

The Two Silences

The list is also defined by what it declines to say.

Deferral and cancellation stay silent while the horizon is truncated. Demand the window excluded could be exactly what the receipt is for, and telling a buyer to cancel an order on that basis is the most expensive mistake a worklist can make. So while truncation is flagged, those two messages are suppressed entirely.

A receipt needed the moment it lands is left alone. The test behind defer and cancel is deliberately conservative: remove the receipt's quantity from every bucket on or after it lands, and see whether anything falls through safety stock. Nothing falls before the end of the window means cancel. Nothing falls until a later bucket means defer to that bucket. Something breaks the moment the receipt lands means say nothing at all, because that order is doing its job.

A Worked Read

A run finishes with 340 items planned and 27 messages. Working the list:

1. One cyclic bill. A sub-assembly whose routing references itself. Note it for the routing owner. Nothing else about that product is usable, so ignore its other rows.
2. No horizon-truncated message. The window covered the demand, so the balances describe the plant.
3. Four past-due releases. Each one is an order that cannot be on time as planned. Decide per item: start now and accept the slip, or find time upstream.
4. Eleven release-order messages. These are the day's real work. Check capacity, then firm them.
5. Three expedites. Supply exists but lands after the breach. Three phone calls, not three orders.
6. Two overdue receipts. Promised before today, not arrived. The plan is counting them as available now, so the balance reads better than the rack does.
7. Six defer or cancel messages. Genuine savings, no service risk. Work them when the urgent list is clear.

Twenty-seven messages, and the ones that change the plant today are the four past-due releases and the eleven releases. That compression is the whole value of the worklist.

Before You Firm, Look at Capacity

The releases are the messages that turn into real documents, and there is one step worth taking first. The Capacity grid on the worklist compares the hours the planned orders would demand against the hours each work center offers, before any of them become real orders.

Read it with its limits in mind. It is a coarse load check, not a schedule: it does not sequence work, split an order across periods, or honor alternates, and its errors point in both directions. Required hours are overstated because a whole order's load lands in the period it starts. Available hours are also overstated because holidays and downtime are not applied. Treat a red bar as a prompt to look before you commit, and a green one as nothing obvious rather than a guarantee. The real answer comes from the finite scheduler, which is why material planning and finite scheduling are two passes.

One Shortfall, One Order

A last read that saves confusion. When an item is short for several consecutive buckets, you get one release message, not one per bucket. The planned receipt is rolled forward into the projected balance, so the later buckets are already covered by the order the plan just suggested.

If you do see a column of near-identical suggestions on one item, the usual cause is that nothing has been firmed yet, which is the same behavior described in why a replenishment suggestion does not lift projected balance until you firm it. Firm the earliest one and read the plan again.