遇到个关于frame和document.write的问题

[dawn06]

代码：
<FRAMESET id="dd" COLS="25%, 50%, *">
<FRAME id="spanFrame">
<FRAME SRC="">
<FRAME SCROLLING="NO" SRC="">
</FRAMESET>
<script language="javascript" defer="true">
window.attachEvent("onload",function(){
spanFrame.document.write( "Something" );
});
</script>

为什么document.write的内容是写到frame的parent页面去，而不是frame

[liuyilidan]

window.parent.frames["spanFrame"].document.write( "Something" );