FYI, for those inclined to take a look, or anyone willing to apply a patch to ZCatalog.Lazy: http://www.zope.org/Collectors/Zope/2326 This bug affects svn HEAD, Zope 2.10.x, Zope 2.9.x. LazyCat.__repr__() calls __getitem__() in such a way that __add__() functionality is crippled (see collector issue) - causes AttributeError. The problem can be worked around in LazyCat.__init__(), which is what the diff/patch attached to the issue does (does hasattr() check and works around appropriately if lazcat doesn't have '_seq' attribute). Any comments/thoughts appreciated. If this looks good, can someone with commit abilities check this in? Thanks, Sean