One Up One Down

This glossary term is part of the SG Systems Global regulatory & operations guide library.

Updated January 2026 • one-up/one-down traceability, supplier-to-customer linkage, lot coding, shipment records, receiving records, rapid trace requests, recall readiness • Primarily Food & Beverage Manufacturing & Distribution (FSMA, SQF/BRCGS audits, customer traceability requirements)

One Up One Down (often written as one-up/one-down traceability) is the minimum traceability discipline where a company can identify (1) the immediate supplier(s) of each ingredient or material used (“one step back”) and (2) the immediate customer(s) or consignee(s) who received the product (“one step forward”). It’s the basic evidence chain that enables rapid containment when a supplier issue occurs or when a customer complaint triggers a recall investigation.

One-up/one-down sounds simple until you try to execute it under time pressure. The typical failure is that a company can show supplier names and customer names, but cannot link them to specific lots, specific time windows, and specific shipments. Without lot-level linkage, one-up/one-down becomes a phone-book list, not a traceability system. Auditors and regulators don’t accept “we buy from Supplier A and sell to Customer B” as traceability. They expect “this finished lot used these supplier lots and shipped to these customers on these shipments.”

Tell it like it is: one-up/one-down is the minimum, not the goal. It’s better than nothing, but it still produces broad recall scope when internal genealogy is weak. The only way one-up/one-down becomes defensible is when you have consistent lot coding, receiving records tied to supplier lots, production consumption tied to internal lots, and shipping records tied to customer deliveries. Without those linkages, you can’t respond fast, and you can’t prove you responded correctly.

“One-up/one-down is the minimum trace promise: who you got it from and who you gave it to—with lot-level proof, not just names.”

1) What “one up one down” actually means

One-up/one-down means you can trace:

• One step back: for a finished lot (or WIP lot), identify the immediate supplier lots of materials used (or at least the supplier batches that fed the product).
• One step forward: for that finished lot, identify the immediate customers/consignees and shipment records where the lot was delivered.

It’s “immediate” because it does not require multi-tier supply chain mapping. It requires reliable linkage at the boundaries you control: inbound receipts and outbound shipments.

2) Why one-up/one-down is the minimum but still high value

One-up/one-down is high value because it’s the fastest containment path when something goes wrong:

• supplier informs you of an implicated lot → you identify where it was used and who received it,
• customer complaint identifies a lot → you identify upstream inputs and potential common-cause sources,
• regulator asks for trace evidence → you can produce a lot-linked supplier and customer package quickly.

It’s also the foundation for deeper genealogy. If you can’t do one-up/one-down reliably, you can’t credibly claim end-to-end traceability.

3) Scope map: what must be linkable for one-up/one-down

For one-up/one-down to work, at minimum you must link identity at these boundaries:

Even though one-up/one-down focuses on suppliers and customers, the internal consumption link is what makes the boundary trace defensible.

4) One step back: supplier linkage and inbound identity discipline

The “one down” part is usually easier than “one up” because inbound lots often come with supplier labels and CoAs. But inbound linkage still fails when receiving is informal.

Defensible supplier linkage requires:

• capturing supplier lot numbers accurately at receipt (preferably scan-based),
• assigning internal lot IDs and linking them to supplier lots,
• linking CoAs and supplier verification evidence to those lots (see CoA verification),
• maintaining quarantine/hold status so unaccepted lots don’t leak into use.

Supplier linkage becomes unreliable when lots are received as “one PO line,” or when supplier labels are missing and operators manually type values without verification.

5) One step forward: customer linkage and shipment identity discipline

The “one step forward” proof is your shipping record. It must connect lots to specific customers and shipments. A defensible forward trace includes:

• shipment identifiers (order ID, BOL, ASN),
• customer consignee identity and addresses (where relevant),
• lot IDs shipped and quantities shipped,
• case/pallet identifiers where used (SSCC),
• date/time of shipment and carrier lane where relevant.

Forward trace fails when shipping is recorded only at SKU level, when mixed pallets aren’t tracked, or when “ship confirm” happens without lot capture.

6) Lot coding: the identity spine that makes one-up/one-down work

Lot coding is the identity spine. If lot codes are inconsistent, you can’t search and link records reliably. Strong lot coding rules are:

• unique across meaningful time horizons,
• consistent across departments (receiving, production, shipping),
• printed and captured on labels and in systems,
• linked to production run definitions (what a “lot” means).

This is why one-up/one-down is often paired with improvements in label verification and scan discipline. If lot identity is wrong, the entire trace chain is wrong.

7) Minimum record set: what you must produce during audits

During audits, “show me one-up/one-down” means you should be able to produce a package containing:

• receiving record showing supplier lot(s) and internal lot assignment,
• production record showing those internal lots were used in a specific finished lot,
• shipping record showing which customer(s) received the finished lot,
• quantity reconciliation (at least high-level mass balance),
• record retrieval speed and clarity.

If you can’t produce all three linkages (inbound → consumption → outbound), one-up/one-down is incomplete.

8) Mixed lots and commingled shipments: where one-up/one-down breaks

Mixed pallets and commingled shipments are common. They are also where one-up/one-down collapses if you don’t maintain identity at the case level.

Common failure patterns:

• multiple lots on one pallet without case-level tracking,
• partial pallets broken down and reassembled without maintaining lot identity,
• repack operations that change case identity without trace.

When this happens, forward trace becomes broad (“everything shipped that day”) rather than precise. That increases recall scope and customer disruption.

9) Rework and WIP: internal gaps that destroy external traceability

Even though one-up/one-down is “external,” internal gaps break it. If rework is used without identity, you cannot confidently connect a finished lot back to the supplier lots that originally produced that rework. If WIP tanks aren’t uniquely identified, you can’t prove which batch fed which finished lot.

This is why mature systems pair one-up/one-down with internal genealogy. One-up/one-down is the minimum; internal genealogy is what makes it accurate.

10) Speed and retrieval: why 24-hour response matters

One-up/one-down is often tied to quick response expectations. In practice, regulators and customers expect rapid retrieval. If it takes you days to assemble, you are not recall-ready.

This aligns with the “24-hour record response” concept: the ability to assemble a trace package quickly using indexed, linked records rather than manual detective work.

11) Mass balance: why quantities must reconcile

Even basic one-up/one-down packages should include quantity reconciliation:

• how much was produced,
• how much was shipped to each customer,
• how much remains on hand,
• how much was scrapped or reworked.

If the quantities don’t reconcile, auditors interpret it as a traceability gap (“product went somewhere”). That’s why mass balance supports the credibility of one-up/one-down.

12) Testing: mock recalls and trace drills as proof

One-up/one-down should be tested. The best tests are mock recalls and trace drills where you select a lot and produce the complete package quickly. This is where hidden gaps show up: missing shipment linkages, missing receiving records, inconsistent lot codes, and mixed pallet ambiguity.

If you never test, you don’t know whether your “one-up/one-down” works. You only know you have data somewhere.

13) Failure patterns: why one-up/one-down becomes a phone-book list

• No lot linkage. Supplier and customer names exist, but not tied to specific lots.
• Shipping not lot-based. Orders ship without lot capture, so forward trace is broad.
• Receiving not disciplined. Supplier lots not captured accurately, so back trace is uncertain.
• Mixed pallets unmanaged. Lots commingled without case-level identity.
• Manual entry reliance. Typed codes create errors and slow retrieval.
• Rework/WIP gaps. Internal identity weak, so external trace is wrong.

One-up/one-down is not hard conceptually. It’s hard operationally because it requires discipline at receiving, production consumption, and shipping—every day.

14) How this maps to V5 by SG Systems Global

V5 supports one-up/one-down by linking inbound supplier lots to internal lots and linking finished lots to outbound shipment records, with traceable genealogy in between. In practice, V5 can:

• capture supplier lot identities at receiving and link them to internal lots,
• record lot-level consumption in production and maintain genealogy,
• link shipments to lots and customer records (BOL/ASN where applicable),
• support mass balance reconciliation for trace packages,
• generate rapid trace reports for audits and mock recalls.

These capabilities align with V5 WMS (receiving and shipping truth), V5 MES (consumption and transformations), and cross-system visibility via V5 Solution Overview.

15) Extended FAQ

Q1. Is one-up/one-down enough for modern audits?
It’s often the minimum, but many programs (SQF, retailer expectations, FSMA recall readiness) pressure-test internal genealogy and mass balance as well. One-up/one-down without internal linkage leads to broad recall scope.

Q2. What’s the biggest improvement to make one-up/one-down reliable?
Lot-level linkage in shipping and receiving. If shipments don’t capture lots, forward trace is weak. If receiving doesn’t capture supplier lots accurately, back trace is weak.

Q3. Do we need case-level identity?
If you ship mixed pallets or break down pallets, case-level identity becomes important. Otherwise your forward trace becomes broad and costly in a recall.

Q4. How do we prove it works?
Run trace drills and mock recalls with random lots and timed performance, including mass balance. If you can produce the package quickly and it reconciles, your one-up/one-down is credible.

Q5. What’s the most common hidden failure?
Rework and WIP identity. Even if your supplier and customer records exist, internal identity gaps can make the external trace wrong or incomplete.

Related Reading (keep it practical)
One-up/one-down becomes operationally strong when paired with lot genealogy (end-to-end genealogy), reconciled quantities (mass balance), and routine testing via recall drills and mock recall performance. If you can’t produce the trace package fast, you don’t have readiness—you have stored data.