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Calling manage_editProperties in a loop for 100 objects should work. But this method needs REQUEST to be passed through. If I just set a REQUEST

try manage_editProperties(Category=['Music','CD','Book'])

you can find that in the API-documentation in zope's online help.

wait, there's a small trick you can use so that you don't need to write your own method which recurses folders. Just go to the "Find" tab of the folder where the instances of your zclasses are and go to advanced search. Select your zclass type for search and put manage_editProperties(Category=['Music','CD','Book']) into "expr:". Zope will find nothing, but the instances' properties are updated after that. cheers, oliver