Generate elements for NULL values with the XSINIL parameter
Applies to: 
SQL Server
Azure SQL Database
Azure SQL Managed Instance
The ELEMENTS directive constructs XML in which each column value maps to an element in the XML. By default, if the column value is NULL, no element is added. But by specifying the optional XSINIL parameter on the ELEMENTS directive, you can request that an element is created for the NULL value. In this case, an element that has the xsi:nil attribute set to TRUE is returned for each NULL column value.