Please help schengen visa?

Hi. It stated in my visa type as MULT which means multiple rigth? And validity is from 05-08-2011 up to 23-08-2011 and the duration is 4 days. I thought that 4 days means 4 days in each country so i booked tickets and places already before the expiration of my visa like 3 days maximum in each schengen country, but just yesterday it just crossed my mind regarding the duration thingy and asked some of my friends. Some said it for each country and some said it is for all. ???:(