This is auto-detected by default, and this option exists mainly
for testing.
-=item --objstore[=DIR]
+=item --objstore=DIR
Enables space savings when the remote C<manifest.js.gz>
includes C<forkgroup> entries as generated by grokmirror 2.x.
If C<DIR> is not an absolute path, it is relative to the
-C<DESTINATION> directory. If only C<--objstore> is specified
-without C<DIR>, then C<objstore> (C<$DESTINATION/objstore>)
-is the implied value of C<DIR>.
+C<DESTINATION> directory. If only C<--objstore=> is specified
+where C<DIR> is an empty string (C<"">), then C<objstore>
+(C<$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