anchor.diff:          }
   
       member self.ToXElem () =
  -        XElem.create self.Name (if self.Data.IsSome then [self.Data.Value] else [])
  -        |> mapOpt self.Condition ^ XElem.setAttribute Constants.Condition
  +        if self.Data.IsSome then
  +            XElem.create self.Name [self.Data.Value]
  +            |> mapOpt self.Condition ^ XElem.setAttribute Constants.Condition
  +            |> Some
  +        else
  +            None
   
   
   let property name data =
  
positive.code:     member self.ToXElem () =
          XElem.create Constants.PropertyGroup []
          |> XElem.setAttribute Constants.Condition self.Condition
          |> XElem.addElement ^ toXElem self.DebugSymbols
          |> XElem.addElement ^ toXElem self.DebugType
          |> XElem.addElement ^ toXElem self.Optimize
          |> XElem.addElement ^ toXElem self.Tailcalls
          |> XElem.addElement ^ toXElem self.OutputPath
          |> XElem.addElement ^ toXElem self.CompilationConstants
          |> XElem.addElement ^ toXElem self.WarningLevel
          |> XElem.addElement ^ toXElem self.PlatformTarget
          |> XElem.addElement ^ toXElem self.Prefer32Bit
          |> XElem.addElement ^ toXElem self.OtherFlags
  
  
  // TODO - Check for duplicate files
  
  
negative.code:             TargetFSharpCoreVersion      = elem    Constants.TargetFSharpCoreVersion
              DocumentationFile            = elem    Constants.DocumentationFile
          }
          //|> mapOpt self.Link      ^ XElem.addElem Constants.Link
          member self.ToXElem () =
              XElem.create Constants.PropertyGroup []
              |> mapOpt (toXElem self.Name) XElem.addElement
              |> mapOpt (toXElem self.AssemblyName) XElem.addElement
              |> mapOpt (toXElem self.RootNamespace) XElem.addElement
              |> mapOpt (toXElem self.Configuration) XElem.addElement
              |> mapOpt (toXElem self.Platform) XElem.addElement
              |> mapOpt (toXElem self.SchemaVersion) XElem.addElement
              |> mapOpt (toXElem self.ProjectGuid) XElem.addElement
              |> mapOpt (toXElem self.ProjectType) XElem.addElement
              |> mapOpt (toXElem self.OutputType) XElem.addElement
              |> mapOpt (toXElem self.TargetFrameworkVersion) XElem.addElement
              |> mapOpt (toXElem self.TargetFrameworkProfile) XElem.addElement
              |> mapOpt (toXElem self.AutoGenerateBindingRedirects) XElem.addElement
              |> mapOpt (toXElem self.TargetFSharpCoreVersion) XElem.addElement
              |> mapOpt (toXElem self.DocumentationFile) XElem.addElement
  
  
  
  // parse the condition strings in property groups to create config settings
  