Validating Relax NG Schema Documents
By default, Relax NG schema files are validated as you type. To change this, open the Preferences dialog box , go to , and disable the Enable automatic validation option.
To validate a Relax NG schema document manually, select the 
Validate action from the
            
Validation toolbar drop-down menu or the  menu. When
            Oxygen XML Developer validates a Relax NG schema file, it expands all the included modules
            so the entire schema hierarchy is validated. The validation problems are highlighted
            directly
            in the editor, making it easy to locate and fix any issues.