Hi all, I'm trying to wrap my head around what the <conditional> tag does...it looks like it doesn't do what I would like. I want to create a tool that allows the user to upload a data file and then have it run through one or more filters. Each filter takes one or more parameters. I was thinking I could do something like this: <inputs> <conditional name="mycond"> <param name="checktest" type="boolean" label="foo" value="yessir"> </param> <when value="yessir"> <param name="param1" type="text" label="bar" value="twunk"> </param> </when> </conditional> </inputs> The idea being, if the user checks the box labeled "foo", a text box labeled "bar" will appear. And I would have several such checkboxes and their accompanying parameters. But what I get is just the checkbox, and nothing happens when I click it. Is it possible to do what I have in mind, and if so, how? Also note that these conditions are not mutually exclusive. A user can select one *or more* filters. So I'm not sure how the body of my <command> tag should look. Is there a way I can just pass every possible parameter to my script like this: myscript.py param1=foo param2=bar If a parameter is not defined (because the user didn't click its associated checkbox), then the script will receive e.g. param1= param2=bar but it can deal with that. I realize I can make several tools and chain them together in a workflow, but that seems like overkill for this use case, and it would be nice if the user could set up their desired filters on one screen. Is this possible? Thanks! Dan