[Mediawiki-l] page abstract delimiter

[f-x.p]

Hi,

I'm pretty sure I've seen somewhere that mediawiki allows a delimiter to
be placed at the beginning of a page to split the resume of the page
from the page itself.

Can someone tell me what this is called, and when to use it ?

Can this summary be displayed under each link in a category page for
example?

Thanks for your help

François