Using Workflow Status Monitor > About this Page, you can review the Page Definition. To enable the about this page link, you must set the FND_DIAGNOSTICS profile system option for your username to enabled. Notice in the BodyRN of the page hierarchy you see the items which contain the data for the workflow message such as the Class Name which comes from the EventDetailsVO and the View Attribute is ClassName.
Fig 5 OLM Workflow Message Framework Page Structure
This shows us how the data items are layed out and that the source of the data is defined in the View Object, in this case there are two VO's involved the EventDetailsVO and the EnrollmentDetailsVO.