A reorder rule says how much of an item a warehouse should hold; replenishment works out what to order so it does, and — if you let it — drafts the requisition every morning. Nothing is ever ordered or sent by itself: the draft still goes through approval (Chapter 14), a purchase order, and your own Send.
Rules. Item *, Warehouse (a specific one, or All warehouses as the organisation-wide fallback), Min qty * (below this the item is short), Max qty (the level to top back up to), Replenish by (Buy — a requisition line, the default — or Make — a draft work order, or a draft subcontracted purchase order when the item's default bill of materials is subcontract work (Chapter 11.10); Make needs an active default bill of materials, Chapter 11.3) and Active. Add rules on the item form (Inventory tracking → Reorder rules → Add rule, one per warehouse) or at Inventory → Replenishment → Manage rules → New rule.
Projected quantity. A rule compares its minimum with what the warehouse will have, not just what it has:
projected = on hand − reserved − committed + on order + in production + requested
- reserved — what confirmed sales orders still have to deliver;
- committed — what released work orders still have to draw from this warehouse (Chapter 11.5); a sales order cannot hold it either, and the refusal names the work order;
- on order — what open purchase orders still have to receive, counting only orders due within the item's lead time (plus the safety days, below); a delivery expected later doesn't help yet;
- in production — what released work orders will deliver here by their planned end, inside the same window;
- requested — what open requisitions have not been ordered.
When projected falls below Min, the quantity to order is Max − projected (Min − projected without a max), lifted to the preferred supplier's minimum order quantity, and Required by is today + lead time + safety days. The lead time is the preferred supplier's (section 10.2, Suppliers), else the item's own Lead time (days). An item replenished by making uses its own lead time and no minimum order.
The Replenishment view (Inventory → Replenishment, also where the Overview's stock alerts lead) lists every rule target that is short — Show every rule target lists them all — with On hand, Reserved, On order, Requested, Projected, Min, Max, To order (Make n for an item made here), Supplier (Made here for one), Lead time, Required by and Drafted in (the draft requisition or draft work order that already carries it); Committed and In production are in the column picker. Filter by warehouse; Draft requisition (Draft orders when something is made) creates one draft requisition per warehouse for everything bought, and one draft work order per item and warehouse for everything made — or refreshes the drafts from an earlier run (quantities and dates updated, items no longer short dropped, new shortfalls added) so you never get two drafts for the same thing. Once a requisition is submitted, or a work order released, it is left alone and counts as requested or in production.
Automatic replenishment — Settings → Inventory → Items → Replenishment → Draft requisitions automatically — runs the same drafting every morning and leaves a notification for everyone who can raise purchases. It is off until you switch it on; Safety days pads every lead time. Review the draft, submit it, raise the purchase order from it (section 6.10) and send that — or, for a drafted work order, check it and Release it (Chapter 11.5): those steps stay yours.