A virtual directory is a way of restricting what pages get shown out of a real directory. It works by tacking on 'virtual' directories after the real directory (ie, as subdirectories) to tell DWiki what you want to see.
Virtual directories restrict pages based on their most recent modification time. There are three versions available:
<year>/[<month>/[<day>]], all as digits. Only pages most recently changed in the time period get selected.
latest/<howmany>. They show just the most recently changed
oldest/<howmany>. They show just the least recently changed
range/<start>-<end>. They show the start'th to the end'th most recently changed page.
All pieces of a virtual directory must really be virtual. If you
have a directory
Foo/ with a
Foo/2005/ subdirectory (or file), you
cannot use the virtual directory
Foo/2005/05/ to see things from May
of 2005 in
Foo/. Moral: let DWiki organize things based on time for
you, don't do it yourself.
Virtual directories are paid attention to by some renderers, which are generally used in some views. You can get the full list in TemplateSyntax.