Learn Document Structure when Schema is not Detected
When working with documents that do not specify a schema, or for which the schema is not known or does not exist, Oxygen XML Author plugin is able to learn and translate the document structure to a DTD. You can choose to save the learned structure to a file to provide a DTD as an initialization source for content completion and document validation. This feature is also useful for producing DTDs for documents that contain personal or custom element types.
When you open a document that is not associated with a schema, Oxygen XML Author plugin automatically learns the document structure and uses it for content completion. To disable this feature, disable the Learn on open document option in the user preferences.