I was looking at the code generated by Visual Studio and I encounter this Global keyword.  Found out that you use this when you want to start the qualification chain at the outermost level of the .NET Framework class library, e.g.:

Global.System.Int32

This is useful if you are in a situation where you have defined a namespace in your code nested in another namespace (e.g. MyNamespace.System) and you have a System.Int32 declaration inside.