...changes are not only responsible for an estimated 80 percent of system failures but, critically, each and every unauthorisedchange can potentially breach regulatory compliance, leaving an organisation wide open to fines and other punishments...
http://www.continuitycentral.com/feature0513.htm
...the implementation of digital signatures. These are embedded within the drawing and are invalidated when any unauthorisedchange is made. A status bar icon called the Validate Digital Signatures icon will warn when changes have been made...
http://www.channelweb.co.uk/personal-computer-world/software/2043508/+exURL+