What is a DXL file? A DXL file is an XML based data storage file created for the enterprise level business collaboration software, Lotus Domino. It contains data related to a Lotus Domino database such as schemas, design elements, view, forms, documents, and the database data itself. XML is a universal file format that can be read by software applications written in any programming language. It is also human-readable and can be opened with any text editor.