When you create a new transformation scenario or edit an existing one, a configuration dialog box is displayed that allows you to customize the transformation with various options in several tabs.
The XProc tab contains the following options:
- XProc URL
- Specify the source XProc file to be used by the transformation. 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. This URL is resolved through the
catalog resolver. If the catalog does not have a mapping for the URL, the file is used
directly from its remote location. - Processor
- Allows you to select the XProc engine to be used for the transformation. You can choose from Calabash for XProc 1.X, Calabash for XProc 3.X, or a custom engine that is configured in the XProc Preferences page.