In some cases we want the user to only be able to select 1 entry in a visualization but at the current moment we don't see any possibility of this in spotfire (except using a script that unmarks every row but one that runs after every marking selection, it itself triggered by a R script). However, we think this would be easily solvable if one could set a limit in the markingscheme for the number of rows that is possible to mark (if user tries to select more the selection is cropped).