In the book 'Beginning XML Databases' there is the following DTD example on page 352:
<!ELEMENT demographics (region*)>
<!ELEMENT region (name, area, country*)>
<!ELEMENT name (#PCDATA)>
<!ELEMENT area (#PCDATA)>
<!ELEMENT country (name, population, area, city*)>
<!ELEMENT name (#PCDATA)>
<!ELEMENT population (#PCDATA)>
<!ELEMENT area (#PCDATA)>
<!ELEMENT city (name, population)>
<!ELEMENT name (#PCDATA)>
<!ELEMENT population (#PCDATA)>
When inserting this in XMLSpy I get an error message saying:
'Element "name" has already been declared' and a reference to www.w3.org saying:
"Validity constraint: Unique Element Type Declaration
An element type MUST NOT be declared more than once."
Anyone that can clarify this?

I haven't got a copy of the book, but it does look like an error on the face of it. Please submit it as an erratum. Instructions are here:

http://www.wrox.com/WileyCDA/Section/id-106035.html

Michael Kay
http://www.saxonica.com/
Author, XSLT Programmer's Reference and XPath 2.0 Programmer's Reference

Thanks, I will.