Author's address: Bertrand Meyer Interactive Software Engineering Inc.(ISE) 270 Storke Road,Suite 7 Santa Barbara,CA 93117 USA 805-685-1006,fax805-685-6869 <meyer@tools.com>,http://www.tools.comAuthor’s address: Bertrand Meyer Interactive Software Engineering Inc. (ISE) 270 Storke Road, Suite 7 Santa Barbara, CA 93117 USA 805-685-1006, fax 805-685-6869 <meyer@tools.com>, http://www.tools.com