Use an External DITA Open Toolkit in Oxygen XML Author
Oxygen XML Author comes bundled with a DITA Open Toolkit, located in the
               DITA_OT_DIR directory. Starting with
               Oxygen XML Author version 17, if you want to use an external DITA OT for all
               transformations and validations, you can open the
                     Preferences dialog box  and go to the DITA
                  page, where you can specify the DITA OT to be used. Otherwise, to use an external
               DITA Open Toolkit, follow these steps:
            
- Edit your transformation scenarios and in the Parameters tab change the value for the dita.dir parameter to point to the new directory.
- To make changes in the libraries that come with the DITA Open Toolkit and are used by the Ant process, go to the Advanced tab, click the Libraries button and uncheck Allow Oxygen to add high priority libraries to classpath.
- If there are also changes in the DTDs and you want to use the new versions for content
                  completion and validation, go to the Oxygen XML Author preferences in the
                  Document Type Association page, edit the
                  DITA and DITA Map document types and
                  modify the catalog entry in the Catalogs tab to point to the custom
                  catalog file catalog-dita.xml.
