Date Format?

[Davey Gaga]

What does this even mean? I found it in the user CP this evening:

Date Format This option allows you to toggle between the Normal, Yesterday/Today or Detailed date format.

 

[Jack's Smirking Revenge]

Normal would put dates on posts (i.e. 28/06/2008 or something similar).
Today/tomorrow would just say "yesterday", "3 days ago", "a week ago" and so on, I think.
Detailed is the default, I think.