function imposeMaxLength(event, object, MaxLen){
    var key = event.keyCode ? event.keyCode : event.which;
    if((key == 8) || (key == 36) || (key == 35) || (key == 37) || (key == 39) || (key == 38) || (key == 40) || (key == 46)){
        // 8 is the keycode for the backspace key
        return true;
    }else{
        return (object.value.length <= MaxLen);
    }
}

//doesn't work
function maxLengthPaste(field,maxChars){
  //event.returnValue=false;
  if((field.value.length + window.clipboardData.getData('Text').length) > maxChars) {
    return false;
  }
  //event.returnValue=true;
} //onpaste='return maxLengthPaste(this,1000);'