function setCheckboxes(the_form, do_check)
{
    var elts      = (typeof(document.forms[the_form].elements['pm_delete[]']) != 'undefined')
                  ? document.forms[the_form].elements['pm_delete[]']
                  : (typeof(document.forms[the_form].elements['selected_tbl[]']) != 'undefined')
          ? document.forms[the_form].elements['selected_tbl[]']
          : document.forms[the_form].elements['selected_fld[]'];
    var elts_cnt  = (typeof(elts.length) != 'undefined')
                  ? elts.length
                  : 0;

    if (elts_cnt) {
        for (var i = 0; i < elts_cnt; i++) {
            elts[i].checked = do_check;
        } // end for
    } else {
        elts.checked        = do_check;
    } // end if... else

    return true;
}