Hi, After a lot of experiments I finally found out how to do this. I am describing the process here in case someone is interested. It really is very simple, but for some reason I could not use the builtin hash() function/methond of zope. Thanks for all the help. a) First create a Python script method (I named it make_key) with 1 argument the object which to hash (I called it text): # make_key(text) # return the positive hash of the input argument return abs(hash(text)) Then in any methond you want to call the hash method, include the following: <dtml-var "make_key(insert_text_argument_here)"> That's it. It really saved me trying to create a database with unique objects (such as big texts) that I could not really use the indexing on them. I know I could use the ZCatalog class, but that will be in a next version :-) I still am in the process of learning zope. May I say that it is the greatest application server I ever saw? Congratulations! Regards Konstantinos Margaritis