그누보드5 리스트목록에서 기간검색값 초기화시키기 도와주세요

<div>        <form name="fsearch" method="get">            <input type="hidden" name="bo_table" value="<?php echo $bo_table ?>">            <input type="hidden" name="sca" value="<?php echo $sca ?>">            <input type="hidden" name="wr_19" value="<?php echo $wr_19 ?>">            <input type="hidden" name="sop" value="and">                        <input type='hidden' name='bo_table' value="<?php echo $bo_table?>">            <input class='ed' type='' id='sdate' name='sdate' size='11' maxlength='10' itemname='시작일' value="<?php echo $sdate?>">              ~            <input class='ed' type='' id='edate' name='edate' size='11' maxlength='10' itemname='마지막일' value="<?php echo $edate?>">             <button type="submit" class="btn2 s">날짜별 검색</button>                                                             <input type="button" value="초기화" onclick="this.form.ed.value='',this.form.$sdate.value=' ',this.form.$edate.value=' ';" />                                </form>        </div>