@huonw I'm not sure if it's appropriate to put limitations like that into `Path`. There's a similar list at the [Naming Files, Paths, and Namespaces](http://msdn.microsoft.com/en-us/library/windows/desktop/aa365247(v=vs.85).aspx) page, but it goes a bit further. It says you can't use characters 1-31 either, except for alternate data streams. You also cannot use "any other character that the target file system does not allow".

Given this, I'm inclined to let the list of particular reserved characters be enforced by the OS, rather than being prohibited via the programming language representation of a path.