Hi, Thanks for the help so far. I'm trying to make a very small knowledgebase kit to get familiar with the ZClasses and ZCatalog. I thought on the following : 1. I make a container ZClass which can contain other container ZClasses and KBItem (see 2) 2. I make a ZClass called KBItem. This contains the information of the problem. It also holds a string which is the same as the category string of its Container ZClass. It also holds a token variable with all the parent container classes. (How can I get all the category strings of all the containers to which the KBItem in this token variable?) How can I make it so, that the KBITems are cataloged on this token variable? Something I'm really not sure of : Can KBItem adjust itself (thus it's category string and token variable) when it is moved? Can a ZClass know when it is moved inside the ZODB? Will the catalog also be auto-updated? Thanks in advance, Tom.