> Index of /publicdir/
> 
> Name                Last modified
> ----                -------------
> <- Parent Directory
> publicfile          17-Aug-2007

"Name" and "Last modified" are themselves links.
Click on Name and you get sorted by name descending. Click again name
ascending.  Likewise for all the other headings.
directory/?N=A sort by Name/ascending ..=D descending
?M modified date
?S Size
?D Description.