-to other pages. It also will include all backreference links in
-them. Each directory will also contain Index page with links to
-all existing pages in current directory and to subdirectories.
+to other pages. It also will include all backlinks in them. Each
+directory will also contain index page with links to all
+existing pages in current directory and to subdirectories.
+
+If ZK_CACHE environment variable contains path to some
+directory, then it will keep caching information for speeding up
+the processes in it. Look for CACHE file for more information.