I’ve tested the four options and now, I understand:

Hi @rvgfox 

It is explained in the table relations guide in this section.

The following are the relationship options.

1. Error: This means that if a related row does not exist in the table, it will be moved to the error table and data may be missing from the valid table instance.
2. Error with physical relation: The relation is stored in the database for other database tools to see. The behavior is otherwise the same as the Error setting. Note that the table needs to have a primary key and a unique index set. If index automation on the table has been disabled, then table indexes will need to be created manually.
3. Warning: TimeXtender copies the invalid record to the warnings table and the valid table instance will still include this data. No data will be missing as a result of the warning, however, the instances that violate the rule may need to be further handled in some other way.
4. Relation: TimeXtender ignores any violations of the check.