. (chdir ):set current drive and current directory from the line.
                set from the parent directory when specified on the line
                of normal file.

            #ifdef W32
                UNC format(\\server1\\dir1\...) is treated under the psude drive "\:".
                "." is applyed to the line of shared folder,
                current drive is set to "\:" and current dir is set to the shared folder.
                Then, \:file means \\server1\dir1\file, \:\file means \\server1\file.
            #endif