Application Express :: Get Part Of URL As Part Of Dynamic Action When Clicking A Button?

I have 3 pages: - Classes: a Classic Report that shows a list of classes and summarises attendance- Class Attendance Report: An Interactive Report that shows a row for each student that attended a class- Attendance Add / Edit Form On the Classes page, the Date value is a Link which passes a filter in the URL to the Class Attendance Report, showing only students who attended the class held on this date On the Class Attendance Report, I want to have a Region Button that, when clicked, goes to the Attendance Add / Edit Form and the Class Date field on this form is automatically populated with the same date value as was being used for the filter on the Interactive Report on the Class Attendance Report Page. So, I click on the Class Date link for 2013-11-01, this takes me to the Class Attendance Report and filters for students who have been already entered as attending on 2013-11-01. If I click on the "Add Attendance" button, it goes to the Attendance Add / Edit form and the Class Date is automatically set to 2013-11-01. I assume I need to do this via a Dynamic Action that runs when the "Add Attendance" button on the Class Attendance Report page is clicked?