General trigger function

Hi all

I read in the doc than a same function can be used for several triggers.
I tried to create a function who updates a field with a timestamp and
another field with the user name. This function is fired by triggers in
several tables.
It only works if updated fields have same names in all tables. I failed to
create a function where fields names are parameters of the function.

What's the way to do that ?
Thanks.

Eric GRIMOIS
Analyste programmeur
SEI - CPAM du Val d'Oise