function userSearch(oSearch, oSelect, oEvent) {
            var searchKeyCode = oEvent.keyCode;
            if((searchKeyCode >47 && searchKeyCode<91) || searchKeyCode == 8 ) { //digits or backspace
                    var searchValue = oSearch.value.toUpperCase()
                    var options = oSelect.options
                    var optLen = options.length
                    var optTest = '';
                    
                    var previousOption = oSelect.getAttribute("previous");
                    if (previousOption != null) {
			options[previousOption].selected = false;
                        oSelect.setAttribute('check', null);
                    }
                  
                    for (var i = 0; i < optLen ; i++) {
                        
                            optTest = options[i].text;
                            if (optTest.toUpperCase().indexOf(searchValue) == 0) {
                                    options[i].selected = true;
                                    oSelect.setAttribute('previous', i);
                                    document.getElementById('assignform').add.disabled=false;
                                    break;
                            }
                    }
            }
            oEvent.returnValue = false;    
    }

    function clearSearch() {
        var form = document.getElementById('assignform');
        form.searchtext.value = '';
    }