As a GS1 Registered Company, all our labels are suitable for overprinting any barcodes, including GTIN, GLN, EAN, QR and Data Matrix. 
GS1 Registered Barcodes:

• GTIN - Global Trade Item Number - the individual barcode number which is internationally recognised and registered for a specific item.
• GLN - Global Location Number - individual barcode number which is used to locate any item to a geographical location from a particular site to as specific as a single bin location in a warehouse store-room.

For more information on GS1 Click Here: 

https://www.gs1uk.org