You must have a default but you can create a blank entry and set it as default.
If you want a dropdown where they can add their own then you want a combo
box rather than a Multiple Selection List Box

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Clay Fox
Qdabra Software
http://www.qdabra.com
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> Why must I have a default value? I just want a drop down list where they can
> have the option of creating their item in the list.
>
> thank you,