[Zope] JavaScript help!

[Peter Be]

Maybe not a Zope specific question but the problem arises only with Zope
DTML.

The documentEdit.dtml page in OFS has this little HTML:
<TEXTAREA NAME="data:text" WRAP="Off"
COLS="50"
ROWS="20"></TEXTAREA>

And what I want to do is trigger a JavaScript that replaces specific
characters in the textarea box to others.
I.e. Replace swedish ö with HTML: &ouml;

The problem is the name of the textarea box!
It is called "name:text"
If I replace the name of the textarea box to say "data", then my JavaScript
works fine.
I have tried to "eval" the box, but to no effect.
Any ideas??

----------
Here's the JavaScript source:
<script language="JavaScript1.2">
<!--
// function changeChars()
// replace swedish chars with HTML ones.

function changeChars() {
 var box = eval("document.manage_edit_form.data:text");
 var datatext = box.value;
var newdatatext;
 newdatatext = datatext.replace("å","&aring;");
 newdatatext = newdatatext.replace("Å","&Aring;");
 newdatatext = newdatatext.replace("ä","&auml;");
 newdatatext = newdatatext.replace("Ä","&Auml;");
 newdatatext = newdatatext.replace("ö","&ouml;");
 newdatatext = newdatatext.replace("Ö","&Ouml;");

 box.value = newdatatext;
}
 -->
</script>


-----------
Here's the JavaScript error:
invalid label.

document.manage_edit_form.data:text
..................................................^