where C<DIR> is an empty string (C<"">), then C<objstore>
(C<$DESTINATION/objstore>) is the implied value of C<DIR>.
+=item --manifest=FILE
+
+When incrementally updating an existing mirror, load the given
+manifest (typically C<manifest.js.gz>) to speed up updates.
+
+If C<FILE> is not an absolute path, it is relative to the
+C<DESTINATION> directory. If only C<--manifest => is specified
+where C<FILE > is an empty string (C<"">), then C<manifest.js.gz>
+(C<$DESTINATION/manifest.js.gz>) is the implied value of C<FILE>.
+
=item -n
=item --dry-run