anchor.diff:          Id = "ServiceControl"
           Name = "Service"
           Remove = Both
  -        Start = Some(Both)
  +        Start = Install
           Stop = Both
           Wait = Yes
       }
  
positive.code:         Id : string
          Name: string
          Remove : InstallUninstall
          Start : InstallUninstall option
          Stop : InstallUninstall
          Wait : YesOrNo
      }
  
negative.code:     | Install
      | Uninstall
      | Both
      | Never
      override w.ToString() = 
          match w with
          | Install -> "install"
          | Uninstall -> "uninstall"
          | Both -> "both"
          | Never -> null
  
  /// These are used in many methods for generating WiX nodes, regard them as booleans
  type YesOrNo = 
  