Q210 I keep receiving function undefined in the following script, why?

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<html>
<head>
<base target="_top">

<script language="JavaScript"><!--
function myfunction() {
    alert("Hello World!");
}
//--></script>
</head>

<body>

<a href="javascript:myfunction()">some link text<\/a>

</body>

Because of the BASE tag in the head of the document, the link is targeting the URL javascript:GetLoc() into the _top window. If the _top window does not contain a JavaScript function called myfunction() then an error message will appear.

Visualise the URL as: javascript:_top.myfunction(), and you'll see why it fails.