- What is the difference between an XML ID and an external ID?
None. Both terms refer to the same thing: external identifiers.
- What type of data files can be used, add-on modules?
Odoo add-on modules can use XML and CSV data files.
- What is wrong in this XML fragment: <field name="user_id">[(4, 0, [ref(base.user_demo)])]</field>?
Three things are wrong: the tag content should instead be in an eval attribute; the 4 command expects the record references in the second element, not the third; and a single record reference is expected, not a list. The correct syntax is: <field name="user_id" eval="[(4, ref(base.user_demo), 0)] />
- Can a data file in one add-on module overwrite a record create in another module?
Yes, in an XML file we can have a <record> element using the complete External ID of the record to replace ...