Serialization – Unique Unit Identification

This topic is part of the SG Systems Global regulatory & operations glossary.

Updated October 2025 • Unit-Level Identity, Aggregation & Traceability • QA, Manufacturing, Warehouse, Regulatory, IT/OT

Serialization assigns a unique, non-repeating identifier to each saleable unit—and, by design, to cases and pallets via parent–child aggregation. The goal is simple: prove which exact pack left your facility, what it contains, and where it went. In regulated industries, serialization is a hard requirement tied to labeling, distribution, and recall effectiveness. In operations, it’s an interlock that blocks bad picks, wrong labels, and untraceable shipments. Practically, serialization must be governed by Labeling Control, verified on-line with Label Verification and Machine Vision Inspection, tied to global identifiers like GS1 GTIN, published through EPCIS, and exchanged with partners via EDI. If unit identity can be printed without being checked, or shipped without being recorded, you don’t have serialization—you have ink.

“A serial number isn’t a promise—it’s a control. If the system doesn’t stop the wrong box, the number is theater.”

1) What Serialization Covers—and What It Does Not

Serialization covers the generation, printing, verification, storage, and exchange of unique identifiers for saleable units, and the aggregation of those units into cases and pallets. It does not, by itself, guarantee product quality, tamper resistance, or anti‑counterfeiting; those outcomes depend on the controls around identity, labels, and movement. A credible program ties serials to the master product code (GTIN), to the batch in the eBMR, and to shipment events published via EPCIS. If any of those links are missing, you’ll struggle to recall, investigate, or defend your labeling.

2) Regulatory Anchors & System Expectations

Serialization supports predicate requirements for identity, labeling, and distribution (e.g., 21 CFR 210/211 for drugs, 820 for devices, and 101 for food labeling), and distribution integrity under GDP. Electronic records must be trustworthy with audit trails and Data Integrity controls; system changes are validated per GAMP 5/CSV. Regulators don’t bless barcodes; they expect evidence that your identifiers are accurate, controlled, and used to prevent harm.

3) Identity Structure—GTIN + Serial + Attributes

At unit level, identity typically combines a product code (e.g., GTIN) with a randomized, non‑guessable serial. Labels may also carry lot/batch and expiry to support recall and Genealogy. Case and pallet identifiers link to their children via aggregation. The golden rule: one item, one serial, one truth. Duplicates, re‑use, or “temporary serials” are shortcuts that create permanent risk.

Store serial objects as first‑class records, with status (commissioned, packed, shipped, decommissioned), links to batch, and parent–child relationships. These records belong in systems that can enforce movement—WMS and MES—not just a standalone database. Serialization data that cannot stop a pick is trivia.

4) The Lifecycle—Generate → Print → Verify → Aggregate → Ship → Decommission

Generate. Systems mint serials (or securely request ranges) tied to the product GTIN and batch. Print. Labels are produced under Labeling Control with effective templates. Verify. Each print is verified with Label Verification and, where camera inspection is implemented, Machine Vision. Aggregate. Units are packed into cases/pallets, building the parent–child tree. Ship. The shipment event publishes serials and their hierarchy via EPCIS and, where required, via EDI. Decommission. Returns, scrap, and rework change serial status with evidence, keeping the record consistent with reality.

Every step must be transactional and auditable with time, user, device, and reason captured per audit trail expectations.

5) Printing & On‑Line Verification—No Print Without Proof

Printing is controlled, not creative. Templates and variable fields live under Labeling Control with version history; jobs are released from MES; and printers are treated like critical instruments. Every serial printed should be verified—grade, data format, and content—using verification and, where justified, vision systems. Failed reads should block progression automatically. Manual “looks good to me” is not verification.

Reprints and voids are governed actions. Reprinting must mark the original serial as voided (not deleted) and link the replacement serial in the record. That linkage matters during complaint and recall investigations.

6) Aggregation—Parent–Child Trees You Can Defend

Aggregation binds units → cases → pallets. The system must record exact child membership and enforce scan challenges when closing a case or pallet. If a case is partially reworked, break and rebuild the tree with a clear history in genealogy (Lot Traceability). Treat aggregation equipment like any other controlled device—qualify it, version its configuration, and capture events in the eBMR or packing record.

Downstream, aggregation integrity enables case‑level scans at receiving while still enabling unit verification if required. Without it, customers open boxes, your dock time balloons, and the cost lands back on you in claims and chargebacks.

7) Warehouse Interlocks—Make Wrong Picks Impossible

Serialized inventory must be physically and logically constrained. In WMS, use bin/location rules and Directed Picking so the picker cannot stage an item whose serials are not commissioned, not released, or not for the market. At Goods Receipt, serialized inbound should be matched to expected serial ranges or EPCIS events; mismatches go to Hold automatically. At ship, the scan must reconcile to the pick list and the published event; no scan, no ship.

FEFO/FIFO rules (FEFO/FIFO) still apply—serialization complements them by proving which pack moved, not just its lot and date. Tie serials into Batch‑to‑Bin Traceability so location, lot, and serial agree at all times.

8) Manufacturing Controls—From Line Clearance to eBMR

Serialization is part of the line’s control logic, not an afterthought. The MES releases jobs, enforces Line Clearance, presents instructions, and gates printing based on step status. The eBMR must show the serial ranges commissioned, counts printed vs. verified, voids/reprints, aggregation events, and final reconciliation before QA approval. If the line can print labels when the step is not in the proper state, you’ve created a leak.

Operator interfaces (HMI) should be simple: scan to prove, print to proceed, block when wrong. Complexity on the screen becomes complexity in the audit trail—keep it crisp and controlled.

9) Sharing Identity—EPCIS & EDI

Serialization is only half done until partners can consume it. Publish commissioning, packing, and shipping as events using the EPCIS standard so customers and regulators can correlate identity to movement. Where trading partners rely on traditional transactions, include serial references in EDI documents. Consistency across EPCIS, EDI, and paperwork is non‑negotiable; if your shipment says “100 units” and your EPCIS shows 98 serials, you’re sending an investigation with every pallet.

For product coding in specific jurisdictions, master identifiers like NDC must be aligned to the product master and the printed data fields. Don’t hard‑code numbers into templates—pull from governed masters.

10) Exceptions, Returns, and Investigations

Wrong print, bad scan, short count—exceptions happen. Treat them as controlled events: open a Deviation/NC, quarantine affected inventory via Hold/Release, and reconcile serials before proceeding. Returns and rework must decommission and (if applicable) re‑commission serials with reason codes. Every change to serial status should land in the audit trail with user, timestamp, and justification to satisfy Data Integrity.

Investigations depend on clean history. If a complaint cites a serial, you should reconstruct the trail from print to ship in minutes—not days—using Genealogy, EPCIS events, and shipping records. If you can’t, serialization isn’t the problem—your system design is.

11) Metrics That Prove Control

• First‑pass scan/read rate at unit, case, and pallet (on‑line and at ship).
• Label verification failure rate and time‑to‑resolution (Label Verification).
• Aggregation integrity: % cases/pallets with complete parent–child trees.
• Reprint/void ratio and re‑label cycle time.
• Pick blocks prevented by serialization interlocks in WMS.
• EPCIS/EDI completeness & match rate vs. physical shipment.
• Recall readiness: time to list all serials shipped for a batch and all recipients.
• Audit/inspection findings related to identity and CAPA closure time (CAPA).
• Link serialization KPIs into broader KPIs and service metrics (e.g., OTIF).

Measure relentlessly. If you’re not tracking read rates, voids, and pick blocks, you’re flying blind and hoping labels save you. They won’t.

12) Common Failure Patterns (and Antidotes)

Free‑text labels and local templates. Antidote: centralize under Labeling Control; block print unless variables are populated from governed data.

Standalone serial DB. Antidote: embed serial checks in WMS/MES so picks and prints are gated by status.

No aggregation or weak rework controls. Antidote: require scan challenges to close cases/pallets; treat break/rebuild as controlled steps with genealogy updates.

Reprint equals duplicate. Antidote: reprint must void the original and create a traceable replacement; never reuse serials.

Unverified printing. Antidote: enforce verification/vision and block step advancement on failed reads.

No published events. Antidote: publish EPCIS and align EDI; reconcile before the truck leaves, not after the complaint arrives.

Weak audit trail. Antidote: ensure all serial status changes are captured with user/time/reason per audit trail rules; review routinely in Internal Audits.

13) Validation & Qualification—Prove the Proof

Serialization spans software, devices, integrations, and labels—so validation must be rigorous. Define requirements (generation, uniqueness, print/verify, aggregation, EPCIS/EDI, decommission) and trace them through risk‑based testing under GAMP 5/CSV. Qualify printers, scanners, cameras, and aggregation stations as equipment (IQ/OQ/PQ). Negative testing is essential: expired templates, duplicate serial attempts, missing EPCIS fields, wrong market configuration—prove the system stops each failure. Re‑OQ after label template or integration changes via MOC.

Evidence lives under Document Control and must be hash‑consistent with production audit trails. “Screenshots in a folder” won’t survive inspections.

14) Implementation Playbook—Fast, Defensible, Scalable

• Model identity. Define GTIN mappings, serial length/format, and status lifecycle; align with markets and customers.
• Lock templates. Move labels into Labeling Control; kill local copies.
• Wire the line. Enforce line clearance, print/verify, and aggregation in MES; write to the eBMR.
• Make WMS a gate. Require scans at pick/pack/ship; block non‑commissioned, non‑released, or wrong‑market serials; segregate via bin rules.
• Publish and reconcile. Emit EPCIS at pack and ship; align EDI counts and serials; stop trucks on mismatches.
• Handle exceptions. Build NC/rework flows; ensure void/reprint logic is audited and simple.
• Validate. Execute IQ/OQ/PQ; challenge edge cases; keep evidence under Document Control.
• Measure. Stand up the KPIs above; roll into APR/CPV; drive CAPA where drift persists.

15) How This Fits with V5 by SG Systems Global

V5 Solution Overview. The V5 platform treats serialization as a first‑class control: configuration is versioned, evidence is attributable, and interlocks (print gating, pick gating, release gating) are testable and reportable.

V5 MES. In the V5 MES, jobs commission serials by GTIN and batch, enforce line clearance, drive print/verify with camera checks, and record aggregation and reconciliation in the eBMR. Steps block automatically on verification failures.

V5 WMS. The V5 WMS makes serialization actionable: inbound matching to expected serials, quarantine on mismatch (Hold/Release), Directed Picking that excludes wrong‑status serials, and ship‑confirmation that fails if scans and EPCIS don’t align.

V5 QMS. Within the V5 QMS, label templates are governed under Labeling Control, changes route through MOC, deviations become NC with CAPA, and print/reprint/audit actions are captured per audit trail rules. V5 Connect publishes EPCIS and supports EDI mappings.

Bottom line: V5 turns serial numbers into plant control. If a serial isn’t valid, the system won’t print, pick, or ship—and the record shows exactly why.

16) FAQ

Q1. Do we need serialization at unit, case, and pallet?
Yes for robust traceability. Units enable item‑level verification and recalls; aggregation at case/pallet enables fast receiving and shipping without opening cartons.

Q2. Can we serialize without on‑line verification?
You can, but you shouldn’t. Without verification, you’ll print unreadable or wrong codes and discover it at ship—or worse, at the customer. Verification is the minimum viable control.

Q3. How do we handle reprints and label damage?
Void the original serial (don’t delete it), issue a replacement, and link the two in the record. Quarantine any physical packs with damaged or unreadable codes until reworked under control.

Q4. What if customers request different data carriers or layouts?
Support with governed templates under Labeling Control. Keep data content consistent (GTIN, serial, lot, expiry) and map carrier differences; validate and version every template.

Q5. How do we prove our serialization system is validated?
Maintain requirements, risk assessments, protocols, and evidence under Document Control; qualify devices (IQ/OQ/PQ); validate software per GAMP 5/CSV; and show production audit trails with negative tests that block failures.

Related Reading
• Identity & Labels: GS1 GTIN | Labeling Control | Label Verification | Machine Vision Inspection
• Traceability & Events: Lot Traceability | Batch-to-Bin Traceability | EPCIS | EDI
• Execution Systems: MES | eBMR | WMS | Directed Picking | Bin Location Management | Goods Receipt
• Quality & Governance: Audit Trail (GxP) | Data Integrity | Document Control | Deviation/NC | CAPA | MOC | Internal Audit
• Validation & Predicate Rules: GAMP 5 | CSV | IQ/OQ/PQ | 21 CFR 210 | 21 CFR 211 | 21 CFR 820 | 21 CFR 101 | GMP | GDP | APR | CPV | KPI | OTIF