2.1.4 Alternate Data Streams
A file system MAY<8> support alternate data streams within a file or a directory. For a general description of file streams, section 1.1.
Every file has a default stream, which is the stream that is referenced when no stream name component is specified as part of the pathname. A directory does not have a default data stream; however, it can have named alternate data streams.
For more information on stream naming, see section 2.1.5; for more information on streams in general, see section 5.