required elements in a DTD

Hi,

I want to define that of a group of elements at least one is required. my current method was working in PHP 4 but now I've got a problem with PHP 5 DOMDocument::validate().
DTD snippet
(<datei> may have up to 4 child elements of what either <file> or <xsl> must be present)

in PHP 5 I get the warning:
is there any way I can define this DTD part differently?

thanks

PS: file codes see http://bytes.com/answers/xml/857093-...validating-dtd

re: required elements in a DTD

Moved to PHP as this is not an HTML question.

codegecko
Moderator in ASP, HTML/CSS

re: required elements in a DTD

I know that the base problem lies within PHP, but I thought I could get help on the DTD matter in the HTML forum. maybe I didn't make that clear enough.

Dormi