Lots, locations, and traceability, explained

Inventory answers two questions about physical stock: what do you have, and where did it come from. Workcell answers both with one idea. Every quantity is the running sum of dated transactions against a lot at a location, and that same log is what lets you trace any unit backward and forward. This primer explains the model; the how-to docs cover the clicks.

The pieces of the picture

Identity: lots and serials

An item tells you what something is. A lot and a serial tell you which one you are holding. A lot is a batch of an item that shares an origin, a single receipt or a single production run, grouped so the quantities stay associated for quality and recall. A serial goes one level finer: it identifies a single unit on its own, for items tracked one at a time. A serial can belong to a parent lot, so the two nest rather than compete.

Place: locations

A location is where stock lives, from a whole site down to a single bin. Every quantity Workcell tracks sits at a location, which is why locations carry flags for what they are allowed to do. A bin can be receivable, pickable, or shippable, and it can be told whether the stock it holds counts toward availability. A quarantine bin holds material physically but keeps it out of availability, so the same on-hand number can be present and unpromisable at once.

Amount: stock on hand

Stock is the on-hand picture: how much of each item sits at each location right now. Workcell keeps three numbers per item per location. On hand is the physical quantity, reserved is the part promised to orders or jobs, and available is on hand minus reserved. You never edit these directly. They are a result, not an input.

Movement: transactions

A transaction is the immutable record of one movement of stock. Receiving adds one, issuing draws one out, a transfer moves quantity from one location to another, an adjustment corrects a count, and a reversal undoes a prior entry. Each transaction names the item, the quantity, the location or locations, and the lot or serial involved, stamped with when it happened. On-hand stock is simply the running sum of these entries.

Why stock is a sum, not a field

It would be simpler to store one on-hand number and overwrite it on every change. Workcell does the opposite on purpose. If stock were a field you edited, a wrong number would erase the history of how it got wrong, and you could never prove where a unit had been. By making stock the sum of dated transactions, every change leaves a permanent, auditable trace, and the count is always reconstructable from its movements. This is why adjustments are posted as transactions too, rather than typed over the figure.

Most of those transactions are not posted by hand. Other parts of the plant drive them. The warehouse posts receipts and transfers, production issues materials and reports finished goods, and shipments draw stock out. Inventory keeps the count and the history honest while the work happens elsewhere.

Traceability falls out of the log

Because every movement is logged against a lot or serial, the history needed for a recall already exists. You do not record genealogy separately. It is the transaction log read in two directions. Where from walks backward to the material a lot was built from, the receipt or work order behind it. Where used walks forward to the lots produced from it and the customer shipments it reached. When a supplier flags a bad batch you trace where used to find every unit affected, and when a customer reports a problem you trace where from to find the exact materials behind it. Workcell traverses that genealogy for you on the Traceability screen.

Why it holds together

Identity, place, amount, and movement are not four separate systems. They are four facets of one ledger. A lot at a location is the thing a transaction moves, the sum of those transactions is the stock, and the chain of transactions is the trace. Get the locations and lots right at the start, post movements rather than edits, and accurate stock and full traceability come for free.

Ready to set it up? Start with Set up locations, then Track lots and serials.