All records in the Odoo database have a unique identifier, the id field.

It is a sequential number automatically assigned by the database. However, this automatic identifier can be a challenge when loading interrelated data: how can we reference a related record if we can't know beforehand what database ID will be assigned to it?

Odoo's answer to this is the external identifier. External identifiers solve this problem by assigning named identifiers to the data records to be loaded. A named identifier can be used by any other piece of record data to reference it later on. Odoo will take care of translating these identifier names into the actual database IDs assigned to them.

The mechanism behind this is quite simple: Odoo keeps a table with the mapping between the named External IDs and their corresponding numeric database IDs. That is the ir.model.data model.

To inspect the existing mappings, go to the Technical section of the Settings menu, and select the...