 Similar to the OSVDB, the NVD publishes impact ratings and categorises material into an index to provide users with an intelligible search system.A variety of commercial companies also maintain their own vulnerability databases, offering customers services which deliver new and updated vulnerability data in machine-readable format as well as through web portals.Examples include Symantec's DeepSight portal and vulnerability datafeed, Secunia's (purchased by Flexera) vulnerability manager and Accenture's vulnerability intelligence service (formerly iDefense).