Hi, I am using the <change_format> tag to decide on the appropriate output file format based on user input. eg: <param name="format" type="select" label="Format" > ...... ...... <data format="txt" name="out" > <change_format> <when input="format" value="tabular" format="tabular" /> </change_format> This works fine except when the input parameter is nested in a <conditional> tag. <conditional name="fileType"> <param name="format" type="select" label="Format" > Usually I would reference this as fileType.format, $fileType.format, ${fileType.format}, but this doesn't seem to work in the input attribute of <when>. Can anyone help me out? Thanks Shaun Webb -- The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336.