Preventing a user from removing the inherited category when adding a document to a folder

Terri_Fisher_(tjfisher@clinapps.com_-_(deleted))

Has anyone done any customization work to prevent a regular user from removing the inherited category when adding a document to a folder? Anything already developed and tested that you'd be wlling to share for a fee? Any tools out there on the market to do this? My client is looking to put something in place quickly and would like to circumvent the time it takes to develop a customization, if possible.