This exit is used to view fields with display types of document and image.
Attachment Methods
public boolean ucViewDocument ( OutputStream out, ImageItemUDF iiu)
This exit may be used to view a document or image field which resides internally within the ExtraView database, stored on the filesystem, or stored in an external repository such as Dropbox, which is integrated with ExtraView.
Also see ucViewAttachment which is used to view file attachments, as opposed to the contents of document and image fields.
For more information, please see here.