As mentioned, applications access peripheral devices through special entries in the file system. The file system code in the Windows CE operating system includes code that recognizes these special file names and redirects file I/O operations to the appropriate stream interface driver.
This section on device file names provides information about the file name formats, prefixes, and indexes you need to establish to develop stream interface drivers. For more information on how to use device file names when developing a stream interface driver, see Writing a Stream Interface Driver DLL.