Extensions Tab
The Extensions tab specifies implementations of Java interfaces used to provide advanced functionality to the document type.
To open the Extensions tab of the Document type configuration dialog box, open the Preferences dialog box , go to Document Type Association, use the New, Edit, Duplicate, or Extend button, and click on the Extensions tab.
Libraries containing the implementations must be present in the classpath of your document type. The Javadoc available at https://www.oxygenxml.com/InstData/Editor/SDK/javadoc/ contains details about how each API implementation functions.