function date_onkeydown() {  
  if (window.event.srcElement.readOnly) return;  
  var key_code = window.event.keyCode;  
  var oElement = window.event.srcElement;  
  if (window.event.shiftKey && String.fromCharCode(key_code) == "T") {
    var d = new Date();       
    oElement.value = String(d.getMonth() + 1).padL(2, "0") + "/" + String(d.getDate()).padL(2, "0") + "/" + d.getFullYear();       
    window.event.returnValue = 0;    
  }    
  if (!window.event.shiftKey && !window.event.ctrlKey && !window.event.altKey) {        
    if ((key_code > 47 && key_code < 58) || (key_code > 95 && key_code < 106)) {     
      if (key_code > 95) key_code -= (95-47);  
        oElement.value = oElement.value.replace(/[mdy]/, String.fromCharCode(key_code)); 
      }
      if (key_code == 8) {   
        if (!oElement.value.match(/^[mdy0-9]{2}\/[mdy0-9]{2}\/[mdy0-9]{4}$/)) oElement.value = "mm/dd/yyyy";     
        oElement.value = oElement.value.replace(/([mdy\/]*)[0-9]([mdy\/]*)$/,function ($0, $1, $2) {
          var idx = oElement.value.search(/([mdy\/]*)[0-9]([mdy\/]*)$/);
          if (idx >= 5) {     
            return $1 + "y" + $2;
          } else if (idx >= 2) {  
            return $1 + "d" + $2; 
          } else {
            return $1 + "m" + $2;  
          }
        } 
      );
      window.event.returnValue = 0;
    }
  }
  if (key_code != 9) {   
    event.returnValue = false;    
  }
}