2.1.372 Part 1 Section 17.14.18, linkToQuery (Query Contains Link to External Query File)

a.   The standard says this element specifies that the query string contains a reference to an external query file that contains the actual query data to be used against the specified external data source for the mail merge.

Word saves this element irrespective of whether the query string actually contains a reference to an external query file or not, and subsequently ignores the element.