The Catalogs tab specifies a list of XML Catalogs, specifically for the edited framework, that are added to list of catalogs that Oxygen XML Author Eclipse plugin uses to resolve resources.
To open the Catalogs 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 Catalogs tab.
You can perform the following actions:
Add- Opens a dialog box that allows you to add a catalog to the list. You can
specify the path by using the text field, its history drop-down, the
Insert Editor
Variables button, or the browsing actions in the 
Browse drop-down list. 
Edit- Opens a dialog box that allows you to edit the path of an existing catalog.
Delete- Deletes the currently selected catalog from the list.
Move
Up- Moves the selected catalog up one spot in the list.
Move
Down- Moves the selected catalog down one spot in the list.