Why does this give a run time error?

[Runtime Error A call to grocery_list received illegal unnamed arg with
source: >]

<defclass grocery_list store_name=required
items='other_unkeyed_args'/>
<defclass grocery_item name=required quantity=1/>

<grocery_list
store_name="Acme Foods"
"apple"
<grocery_item name="milk"/>
<grocery_item name="pears" quantity=3/>
/>

This was taken from the water book.

Thanks,
Susan

======================================================================
Susan G. Conger Custom Windows & Macintosh Development
President Web Site Design & Development
YOERIC Corporation Database Design & Development
256 Windy Ridge Road
Chapel Hill, NC 27517
Phone/Fax: (919)542-0071
congers@...
www.yoeric.com