What is a GLN (Global Location Number)? A guide for UK suppliers

The request usually arrives in a retailer's onboarding pack. A UK retailer expects four things from a new supplier: "a Global Location Number, a Supplier Number, barcodes that scan and, where asked, pallet labels", as the retail supplier playbook sets out. If a retailer asked for your "EDI number", it usually means your GLN, and our explainer covers the other codes that phrase can mean.

What is a Global Location Number?

GS1 calls the GLN "the GS1 Identification Key used for any location (physical, operational or legal) that needs to be identified for use in the supply chain." It is a globally unique number that points to master data about a location.

That is why it replaces addresses in messages. In GS1's words, names and addresses "do not need to be communicated with every transaction." The details are shared once, stored in each partner's system and looked up by the GLN from then on.

GS1 calls GLNs "a key concept in EDI", and the number is recognised by UN/CEFACT and by ISO 6523.

What can a GLN identify?

A GLN can identify four things, according to GS1. Two describe a party, the "who". Two describe a location, the "where".

• Legal entity. Any business, government body, charity, individual or institution with standing in law and the capacity to enter contracts. A legal entity needs its own GLN when its legal name, address or registration number differs from other legal entities and there is a business need to identify it across organisations.
• Function. "An organisational subdivision or department based on the specific tasks being performed", such as an accounts receivable department. If no functions are defined, the legal entity GLN represents all of them.
• Physical location. "A tangible place that may be represented by an address, coordinates, or other means." A warehouse, a warehouse gate, a delivery point or a single room can each carry one, and so can a mobile location.
• Digital location. "An electronic (non-physical) address that is used for communication between computer systems", such as an EDI mailbox.

How are the 13 digits of a GLN built?

A GLN has three parts, and its length never changes.

1. GS1 Company Prefix. Allocated by a GS1 Member Organisation to the company that allocates the GLN. UK-issued numbers usually start 500 to 509.
2. Location reference. Set by the party that defined the location. Its structure is at that party's discretion.
3. Check digit. The 13th digit, calculated from the first 12.

The prefix and the location reference share the first 12 positions between them. The check digit "helps to detect and reject incorrectly composed values", for example a digit mistyped during manual entry. It uses the same algorithm as GS1 barcodes: the digits are multiplied alternately by 3 and 1 and summed, and the check digit is derived from that total. GS1 offers a check digit calculator on its GLN page, and the check itself must run in the application software.

Who allocates a GLN, and can it be reused?

Your business allocates its own GLNs from the GS1 Company Prefix that GS1 UK gives it. The rule is that the party that defined the location allocates the GLN. For a physical location, that is the owner or the primary user. GS1's example is a shopping centre: the owner of the centre allocates its GLN, while a retailer leasing a unit allocates the GLN for its own store.

A small supplier can start with one number. GS1 says companies with limited needs "can successfully utilise a single GLN" to identify a legal entity, function, physical location and digital location at once. It also warns that this approach can cause issues as the business scales, so add GLNs as you add sites.

Once a GLN is in use, it stays with what it identifies. "An allocated GLN SHALL NOT be reallocated to another party and/or location." That non-reuse rule took effect on 1 July 2022, and GS1 lists narrow exceptions, such as a GLN that was "never published in an externally accessible manner".

How do I get a GLN in the UK?

You register through GS1 UK. Registration gives your organisation a GS1 prefix, and from it you generate a GLN for each location and a GTIN for each product line, following GS1's numbering rules. Registration is online, and GS1 UK asks for your company details before allocating a prefix.

GS1 UK is one of GS1's local Member Organisations, and members assign GLNs using the 13-digit structure. There is no GLN price to quote here: the number comes with your GS1 UK registration, so check the current terms with GS1 UK directly.

How do I find my existing GLN?

Your GLN and GTINs sit in your GS1 UK account. If you cannot locate it, your EDI provider can usually confirm it from your existing account setup.

Where does a GLN appear in an EDI order?

A GLN appears in two places in an EANCOM order: the envelope and the party details. EANCOM is "a GS1 subset of the UN/EDIFACT standard", and it ties trade items and logistics units to the GLNs that identify trading partners.

• The envelope. The interchange header, which GS1 compares to "a physical envelope", can identify the sender and the recipient by GLN.
• The parties. The order's party segment carries the buyer, the supplier, the delivery party and the invoicee, each identified by a 13-digit GLN. Identifying the buyer and supplier is mandatory. Names and addresses are only used when a code cannot be used or the full address is required.

GS1's own ORDERS manual gives this illustrative example, with the buyer, supplier and delivery party:

NAD+BY+5412345000013::9'NAD+SU+4012345500004::9'NAD+DP+5412345000013::9'

In practice, a retailer's buying system sends a purchase order carrying its own GLN as the buyer and your GLN as the seller. GLNs also mark the ship-to, bill-to and deliver-to locations, so one order can point to three addresses without spelling any of them out.

Where else does a GLN appear: labels and Peppol?

On pallet labels, the GLN of the consignee, the ship-to or deliver-to point, is encoded in a GS1-128 barcode under Application Identifier (410). Scanning it automates shipping and cross-docking.

In eInvoicing, the GLN is one of the identifier schemes a Peppol participant can be addressed by: scheme code 0088 in the Peppol BIS Billing 3.0 code list. Transalis is an authorised Peppol Access Point using AS4, so the same number can route an invoice as one more supply-chain document.

What goes wrong with GLNs during EDI onboarding?

A mismatched GLN on a purchase order is one of the most common reasons a new EDI connection fails testing before it goes live. During onboarding, your provider will usually run test messages with each new trading partner to confirm every GLN is correct before you go live.

The non-reuse rule matters here too. As a rule, a retired site's GLN is not handed to a new site, so a new location usually needs a new number.

How does Transalis handle GLNs in EDI?

You share your GLN with Transalis once, and Transalis uses it to route messages and data to the correct endpoints for your organisation. Transalis is a managed outcomes provider for B2B integration, EDI and eInvoicing, and testing with each trading partner confirms your GLNs before the connection goes live.

After go-live, Transalis DataTrack™ shows individual messages, so you can see where an identifier does not match and correct it before it causes a bigger problem further down the chain. Transalis OpenEDI™ connects you to more than 15,000 live trading connections on a fixed-cost basis.

Connect once, reach anyone. Secure your connection in a call with the team, GLN in hand.