"Directories" in the DFS are single character prefixes on filenames - such as codice_21 in codice_34 - used to group files. The arrangement is flat and a default directory of codice_35 is used instead of a root directory. On requesting a catalogue of the disc (with the codice_36 or codice_37 commands), files in the current directory are shown with no directory prefix in one block, and below that are listed all other files in a second block, with their directory prefixes visible. For example, (from Acorn DFS - third party DFS implementations may vary slightly):