Custom Sort function allows you to specify a custom sort order when a column is sorted (as opposed to the default alphabetical or numbered sort).
This is ideal for both columns where the default sort order doesnt make sense (e.g. a 'Ratings' or 'Tenor' column) or where each user will have their own preffeed non standard sort (e.g. Sector or Currency).
This example we created Custom Sorts on 'Employee' and 'Contact' columns. Click the header to sort and you will see that they get sorted according to the Custom Sort order (and not alphabetically).