QUICKFORM: How to detect changed form entries?

Hi, is there a feature in QF which returns the names of elements which got changed by the user? I think about implementing a QF input mask which gets data from a data base. If the user changed only one or a few of the input fields I want my application to only update these changes on the data base server and leave the others untouched. That's why I need to find out what the user modified, which can be certainly done by storing the starting values and comparison with values after form submission. Marko