XF 1.1 User prefixes?

[Morgain]

I just discovered that the list of members in admin has an interesting looking bar at the top.



It looks like it could be useful. So how do I give users a prefix?
How can I use that filter box?

 

[Syndol]

It's not an actual prefix. It's a filter for the first few characters of a name.
For example, take the following two names:
XXX
YYYXXX

If you enter xxx into the search box, the returned value would be:
XXX
YYYXXX

But if you tick the prefix checkbox you will only get:
XXX