Meet The Latest GS1 Key: The Global Model Number (GMN)

GS1 makes modifications and additions to their General Specifications every year—sometimes even twice a year.  The latest is version 19 and was published in January 2019.  The “GenSpecs” contain the full detailed definitions of every GS1 “key” and every GS1 barcode.  While it doesn’t contain the definitions of every GS1 standard, it is the catch-all specification for their traditional core—mostly barcode related—standards.  This is where GS1’s keys are defined, included the Global Trade Item Number (GTIN, Application Identifier, or AI = 01), Global Location Number (GLN), Serial Shipping Container Code (SSCC, AI = 00), Global Returnable Asset Identifier (GRAI, AI = 8003) and all the others.  Last year (GenSpecs version 18) GS1 introduced their latest key, the Global Model Number (GMN, AI = 8013).  It’s an important addition, particularly for healthcare.  Let me explain.

The GS1 GenSpecs says this about the GMN:

“A product model is a base product design or specification from which a trade item is derived. The trade item inherits major features/functions from the base model. The GS1 Global Model Number (GMN) is the GS1 identification key used to identify product models from which trade items are derived. The GMN comprises the GS1 Company Prefix and a model reference. The model reference is alphanumeric and its structure is left to the discretion of the brand owner who assigns it.

“This element string, once assigned to one product model, SHALL NOT be reissued to another. The GMN SHALL NOT be used to identify a trade item.”

When you think about it, it’s kind of surprising that it took GS1 this long to realize it needed to add something like the GMN to “The GS1 System”.  I didn’t notice the deficiency.  The FDA didn’t notice the deficiency when they produced the Unique Device Identification (UDI) final rules (see “InBrief: FDA Publishes Final UDI Rule”).  It took the European Medicines Agency (EMA) to discover something was missing and to have the European Commission (EC) mandate the creation of, what they called, a Basic UDI Device Identifier, or, Basic UDI-DI, or, BUDI-DI (see GS1 “Call to Action:  New EU Unique Device Identification system requires new identifier: Basic UDI-DI”.  See also Karen Fleshman’s comments about it in “The Fall Global GS1 Healthcare Conference”).

That EC mandate led directly to the creation of the GS1 GMN and its formal addition to the GS1 GenSpecs.  According to GS1:

For regulated healthcare medical devices, the following applies:

When used for the unique identification of medical devices, the GMN’s default, global data title SHALL be Basic UDI-DI or BUDI-DI. Other data titles which occur at local levels may be recorded in GS1 guidelines.

“In regulated healthcare, the Basic UDI-DI (BUDI-DI) serves as the key element to allow the linkage of the different modules of the European Database for Medical Devices (EUDAMED). Per the EU Regulations, BUDI-DI is ‘The primary identifier of a device model. It is the DI assigned at the level of the device unit of use. It is the main key for records in the UDI database and is referenced in relevant certificates and EU declarations of conformity. (As defined by the European Medical Devices Regulation (EU MDR) and European In-Vitro Diagnostic Medical Devices Regulation (EU IVDR).’”

The format of the GMN is:

Take from GS1 General Specifications, Figure 3.9.13-1. Click on image to enlarge.

Like all GS1 keys, it starts with your GS1 Company Prefix (GCP) (see “Your GS1 Company Prefix: An Enterprise Resource”).  Your GCP is always numeric only, but the Model Reference field of the GMN is variable length (up to a total length of the GMN to 30 characters) and can be alphanumeric (that’s what the X’s means in Figure 3.9.13-1 from the GenSpecs, shown above). 

For a one page executive summary of the GS1 GMN, see GS1’s “Global Model Number (GMN)“.

The GMN is the first and only GS1 key that allows the use of alphas in a “reference” field (the field immediately following a GCP in a GS1 key), which is a bit of a departure for GS1—and a paean to the medical device community which has been using alphas in their part numbers for decades (take that HIBCC!).

BUDI-DI is an important concept, providing an identifier for an idealized product design or concept, but not going so far as to ever be a trade item reference.  That’s why a GTIN cannot serve as a BUDI-DI within the GS1 System.  They had to come up with a new identifier for this purpose.  When it exists, the GMN should be used in the master data for trade items.  It may have value in adverse event reporting and whatever the equivalent is to pharmacovigilance in medical devices. The GenSpecs state emphatically that GMN must never be encoded into a barcode or printed on a label of a trade item for medical devices. 

So my question is, will the FDA add the BUDI-DI concept—which the GS1 GMN can be used for—to the US UDI requirements?  It seems like it would be helpful in the US supply chain as much as it is in the EU.  I’m going to find out this week when I attend the UDI Conference in Baltimore.  The FDA UDI staff sponsor and attend this event every year (they actually have a booth in the tradeshow) and it is a great place to learn about UDI and get your questions answered.  That’s what I’m going to do.  I’ll update this essay with what I learn at the event this week.  I hope to see you all there.