This setting is only valid if the NESTED attribute is also TRUE.
When working with large ProDataSets, omitting foreign keys in nested child records can yield smaller XML documents, more efficient network transfers, and performance gains with the READ-XML( ) and WRITE-XML( ) methods.
Care must be taken when deciding to use this feature. The READ-XML( ) method automatically populates foreign keys in nested child records with the value in the outer parent record when the foreign key is omitted from the XML document. Unless you are sure that the receiver of the XML document will do the same, you should not use this option in your nested data-relations.
For example, while .NET can read this XML document and populate an ADO .NET DataSet, it will create rows in the child DataTable with a null value for the foreign key field.