Selecting the option in the Alignment window's Edit
menu or pressing 'CONTROL+D' brings up a dialog box
asking you to select a threshold. If the percentage identity between
the aligned positions of any two sequences in the visible alignment
exceeds this value, the shorter sequence is discarded.
Note: The redundancy calculation is done when the dialog box is opened. For large numbers of sequences this can take a long time as all pairs have to be compared.