Restriction based on attribute value

My schema defines an element images consisting of child elements image.  Each image has an attribute context, an enumeration of "viewing", "viewing-1024", "viewing-800", "printing".  I would like to define a new type of images based on images.  The new type must have at least two image child elements, one with context="viewing-1024" and one with context="viewing-800".  How can I do this, perhaps by restricting the original images?

Thanks,
Richard R. Liu

Richard R. Liu
IVHS - Content Mgmt Fachstelle
Hochstr. 16, 2149
Basel
Tel. 061/288 76 89 

Received on Monday, 3 May 2004 07:48:59 UTC