Yesterday at the executive meeting, you said that you and your colleagues on the IT side of the house have been studying how to $$harden$($I think that$$s the word you used$)$ the operating system for our integrated supervisory control and data acquisition $($SCADA$)$ systems for the water treatment plants we serve. How vulnerable are SCADA systems today? Can you give me a sense of what the key issues are in evaluating and improving these operating systems to resist attacks and failures?