I've searched the archives and zope.org, but I can't find the answer tho this problem (i think this is partly because it's hard to express it in a few search-terms.) : I have a ZClass (subclassed from ZCatalogAware) with some properties. The properties are indexed in a catalog and the indexing works fine for most of them. One of the properties however is a multiple selction listbox, and this means that the property-type is a list. The ZCatalog doesn't seem to like this. It will not report any errors, but any searches in which the property is involved deliver a result set that is way too small. (I suspect that only those records are returned for which the multiple selection is empty.) Now as it turns out, the multiple selection itself was unnecessary as 99% of the records will have only a single value in the field. My question therefore is twofold: Is this behaviour expected and am i too green to get how to index the list property (i suspect this is it,) or is it a bug? In the unlikely latter case, is there a way to change the type of the property without losing the data? (I'm not using an external datasource yet, as this is just a prototype site, but the dataset is large enough that i don't want to enter it again.) TIA, eric casteleijn