CSS文本样式：软件序列号式的输入框

<script?for="T"?event="onkeyup"> 
if(value.length==3)document.all[event.srcElement.sourceIndex+1].select(); 
</script> 
<input?name="T"?size="5"?maxlength="3">—<input?name="T"?size="5"?maxlength="3">—<input?name="T"?size="5"?maxlength="3">—<input?name="T"?size="5"?maxle