About 1. find UUID of current history in tool XML wrapper? (Ben Bimber) 2. Re: find UUID of current history in tool XML wrapper? (John Chilton) I think this will work for you, I've simplified the code. I was able to do this somewhat circuitously (=bonfire of time) for my upcoming Versioned Data tool. In your tool XML definition file: <param name="history_id" display="radio" type="drill_down" dynamic_options="vdb_init_tool_user(__trans__)" /> ... <code file="versioned_data_form.py" /> Not sure if making history_id a hidden field would work (I seemed to recall __trans__ variable only exposed to select param). And in a script named versioned_data_form.py we have: def vdb_init_tool_user(trans): """ ... ALSO: squeezing history_id in this way since no other way to pass it. "trans" is provided only by tool form presentation via <code file="..."> ... """ history_id = str(trans.security.encode_id(trans.history.id)) items = [ { 'name': 'think of something to say here', 'value': history_id, 'options':[], 'selected': True } ] return items