When using the 'Insert References / Data Containers' functionality, by convention, all non-NODE rows following a NODE row, represent data owned by the NODE. The 'Data Owner Node' option allows you to make the relationship between the NODE and non-NODE rows more explicit. For each row representing a data container object, a reference object, or a classification product link object, the owner node ID can be included in the 'Data Owner Node' column.
For details on using the options in the 'Insert References / Data Containers' group, refer to the Insert References - Data Source Outbound topic (here) and the Insert Data Container - Data Source Outbound topic (here).
