Clutch disc washer direction

Hi, i am refurbishing a clutch and am puzzled with the following:

on the technical drawings (like the sip exploded views) the copper/brass washer goes with the ridge down to the base plate. However every 'clutch rebuild' video or manual i find mentions to put this ring with the ridge up ... that puzzles me especially cause of the importance that is given to this ring in these manuals ... 

so what is the right position??