[Zope] Sorting mod.time with dtml-in?

[bak (kedai)]

>
> Assuming version 2.3, try:
>
> <dtml-in expr="subdir.objectValues()"
> sort_expr="bobo_modification_time()">
>
> since it is a method.
>
> hth,

what's the difference between using sort and sort_expr?  the sort=something 
has been there since forever :) and i have been using it in my codes.  is it 
something bad?

thanks