Comment 2 for bug 2112

I tried to compare top-level calendar add with a add link incalendar,it includes the variable in the adress:
https://launchpad.net/calendar/+add?field.dtstart=2005-02-01%2009:00
This is the variable wich is misding in the top-level.
This could be solved by several ways, I dont know wich one is the best way to do it, any sugestion?