Access Control - Extension Proposal

(Based on existing functionality detailed at AccessControl)

New Requirements

• Assigning rights by user groups (not just by user).
• Lock down of the an 'extra' field, so that only authorized users can make it a particular value. e.g. Only 'FCO editors' and 'admins' can set the 'department' field to the value 'Foreign and Commenwealth Office'.