function iso8601totime($iso8601) {
        /*

         date-time       = full-date "T" full-time

         full-date       = date-fullyear "-" date-month "-" date-mday
         full-time       = partial-time time-offset

         date-fullyear   = 4DIGIT
         date-month      = 2DIGIT  ; 01-12
         date-mday       = 2DIGIT  ; 01-28, 01-29, 01-30, 01-31 based on
         month/year
         time-hour       = 2DIGIT  ; 00-23
         time-minute     = 2DIGIT  ; 00-59
         time-second     = 2DIGIT  ; 00-59, 00-60 based on leap second rules
         time-secfrac    = "." 1*DIGIT
         time-numoffset  = ("+" / "-") time-hour ":" time-minute
         time-offset     = "Z" / time-numoffset

         partial-time    = time-hour ":" time-minute ":" time-second
                                            [time-secfrac]
         */

        $regs = array();
        /*         [1]        [2]        [3]        [4]        [5]        [6]  */
        if (preg_match('/^([0-9]{4})-([0-9]{2})-([0-9]{2})T([0-9]{2}):([0-9]{2}):([0-9]{2})Z$/', $iso8601, $regs)) {
            return mktime($regs[4],$regs[5], $regs[6], $regs[2], $regs[3], $regs[1]);
        }
        // to be done: regex for partial-time...apache webdav mod never returns partial-time

        return false;
    }