From Online Manual
Custom Titles allow members with the relevant permission to create a special title for themselves. This will be shown underneath the name when they make a post or send a personal message.
- CoreISP - Username/Displayname
- Super l33t Admin - Custom Title
- Systems Administrator - Primary Membergroup
By default, SMF has Custom Titles enabled and allows anyone that has the proper permissions to edit/add custom titles. These can be edited from (Profile > Forum Profile > Custom Profile).