+=head1 UPLOADING AND DOWNLOADING FILES
+
+For commands such as C<upload>, C<download>, C<tar-in>, C<tar-out> and
+others which upload from or download to a local file, you can use the
+special filename C<-> to mean "from stdin" or "to stdout". For example:
+
+ upload - /foo
+
+reads stdin and creates from that a file C</foo> in the disk image,
+and:
+
+ tar-out /etc - | tar tf -
+
+writes the tarball to stdout and then pipes that into the external
+"tar" command (see L</PIPES>).
+
+When using C<-> to read from stdin, the input is read up to the end of
+stdin.
+