+wxFileName currently supports the file names in the Unix, DOS/Windows, Mac OS
+and VMS formats. Although these formats are quite different, wxFileName tries
+to treat them all in the same generic way. It supposes that all file names
+consist of the following parts: the volume (also known as drive under Windows
+or device under VMS), the path which is a sequence of directory names separated
+by the \helpref{path separators}{wxfilenamegetpathseparators} and the full
+filename itself which, in turn, is composed from the base file name and the
+extension. All of the individual components of the file name may be empty and,
+for example, the volume name is always empty under Unix, but if they are all
+empty simultaneously, the filename object is considered to be in an invalid
+state and \helpref{IsOk}{wxfilenameisok} returns {\tt false} for it.