The r attribute of a cell defines the reference the cell is pointing to in a style similar to A1. Setting this attribute is optional but when set to an empty string, it cannot be imported - an ArgumentException is thrown with message "cellName" by the Guard class in NameConverter.ConvertCellNameToIndex(). Here is an example of such a definition: <row r="1" spans="1:12"> <c r=""/> </row> MS Excel and Libre Office can open such documents.