Key Concepts
Understanding these six concepts will make every other part of Atrope click.
Items
An item is anything you buy, sell, make, or store. Each item has a unique item number (e.g. TBL-NOTE-08), a base unit of measure, and a set of tracking flags:
- Lot-tracked — stock is grouped by production or supplier batch
- Serial-tracked — each individual unit has a unique identity
- Expiry-tracked — lots carry a best-before or use-by date
Lots
A lot (also called a batch) is a group of identical items that were produced or received together. When an item is lot-tracked, you can’t just say “I have 50 gloves” — you have to say which lot they’re from.
Lots carry:
- A lot code (your internal reference) and optionally a supplier lot code
- Manufactured and received dates
- An expiry date (if the item expires)
- A status: Active, Quarantine, Expired, or Exhausted
Serial Units
A serial unit is a single, uniquely-identified item. Serialised tracking is used for high-value or regulated goods where you need to know the exact history of each individual unit — which order it came in on, where it was stored, which shipment it left on.
Facilities and Locations
A facility is a physical site: a warehouse, distribution centre, store, or production floor. Every facility has a location tree — zones → aisles → racks → shelves → bins.
Stock always lives at a specific location. Transfers move stock between locations, either within the same facility or between facilities.
Stock Statuses
Not all stock on hand is usable. Every unit carries a stock status:
| Status | Meaning |
|---|---|
| Available (AVL) | Can be allocated to orders |
| Quarantine (QRN) | Held for QA inspection — cannot ship |
| Damaged (DMG) | Written down but tracked |
| Reserved (RSV) | Allocated to a specific order |
| In Transit (TRN) | Moving between locations |
Reorder policies and on-hand dashboards count only Available stock by default.
The Inventory Ledger
Every stock movement — receipt, shipment, transfer, count, adjustment — posts one or more ledger lines. Each line records:
- Which item and lot (or serial)
- The location affected
- The quantity delta (positive = in, negative = out)
- The source document (PO number, SO number, transfer ID, etc.)
- The user who posted it and when
The ledger is immutable: corrections are made with reversing entries, never by editing existing lines. This gives you a complete, auditable history from day one.