Name of the file/writer, including extension
URI for this virtual file
Optionally returns an implementation-dependent "version" token.
Optionally returns an implementation-dependent "version" token. Versions are compared with ==. If non-empty, a different version must be returned when the content changes. It should be equal if the content has not changed, but it is not mandatory. Such a token can be used by caches: the file need not be read and processed again if its version has not changed.
A virtual input file.