Hi, I am working on a tool that allows to filter on a selected set of contrasts. The contrast names are read from the second column of a history item. In order to allow selection of individual filters for each contrast, I am using the <repeat> tag. Now I would like to make sure that the user selects each contrast at max one time. Can I use the <filter ...> to remove the contrasts that have already been chosen from the selection? Or is there a more elegant way? <repeat name="contrasts" title="Contrast" min="1" max="3"> <param name="contrast" type="select" label="Contrast to filter on" multiple="false"> <options from_dataset="edgercont"> <column name="name" index="1"/> <column name="value" index="1"/> </options> </param> <param name="lfc" type="float" label="Linear fold-change" value="2.0" /> <param name="pval" type="float" label="p-value cutoff" value="0.001" /> </repeat> Thanks for your help in advance Tim