What are identifiers
Identifiers are used to create indexes of values of attributes that can be used from the API to find products, variants or categories based on a unique identifier in an external system.
As any update request to Struct PIM requires the internal id of the resource being updated, a mechanism must exist to resolve this internal id based on a known key. For this, implementors will create identifiers in Struct PIM defning the maps between externally known keys and the internal id of the resource in Struct PIM.
Example: In an ERP system, a product has a SKU, which is used to uniquely identify the product. An integration job created the product in Struct PIM and the SKU is written to a "SKU" attribute on the product. Later, when the integration job runs again, it needs to update the product. In order to update an existing product, the internal id assigned to the product in Struct PIM must be known, but the integration job only knows the SKU from the ERP system.
Because an identifier has been setup on the SKU attribute in Struct PIM, the integration job can request the internal id of the product based on the SKU it knows from the ERP system. From the internal id it is able to update the product in Struct PIM