GCID P roduct IDs. When you enroll your products in the Brand Registry, they are automatically assigned a unique product ID called the Global Catalog Identifier (GCID). Brand owners can find their products' GCIDs in their inventory reports. The GCID can be used in place of the standard product IDs.This allows the seller to list their products on Amazon even if they don't have a standard product ID, such as a UPC or EAN. On your ChannelAdvisor template, you can map the GCID as your primary Product ID.o address this concern, Amazon created the the Amazon Brand Registry program for sellers who manufacture or sell their own branded products. The program's goal is to make it easier for sellers with their own brands to manage those brands and list their products on Amazon.com.