FOREIGN KEY: MATCH FULL

Hi,

What does it mean the MATCH FULL parameter in a foreign key specfication
?

It seems it is only valid for a multi-column foreign key: What's a
multi-column foreign key ?

I've tried to search this in Bruce's book but I have a lot of problems
to connect to it at   http://www.postgresql.org/docs/awbook.html

Thanks,

Gabi :-)