For the various test definitions parameters, currently, the UI can only set the values to literal ones. For example, if you try to set the data table path, you can choose a path using the open file dialog. This value is a literal path to the full directory. WET offers some powerful parameter substitution capabilities using which you can parameterize these configuration items. WET UI should be allowed to take advantage of this paramterization. To allow this, the various wet ui objects (like TestDefinition panel, etc.,) should have two variables for each variable - one the value being set in the TestDefinition file and another the 'parsed value' of this. Whenever the TD Panel tries to operate on this parameter, it should use the parsed value - Say : parameter is set to eval #{ENV['res']}/depot/my_depot.xml, and the ENV['res'] = C:\mydepots\, then when the object depot file is saved, it should be saved to c:\mydepots\depot\my_depot.xml Also, dont try to do a reverse mapping when creating scripts - this definitely will open up an avenue for various issues. By Reverse mapping, I mean: If user types "c:\mydepots\depot\my_depot.xml" in any of the function dialogs or for one of the items in the td panel, then DONT try to convert this automaticaly to eval #{ENV['res']}/depot/my_depot.xml