Viega 8350.32 Instructions For Use Manual page 21

Handling
Score the revision shaft along the edge of the tiles with a knife.
Angle the knife to do this so that the cut is made flush to the surface
of the wall.
Cut the corners of the revision shaft vertically through to the wall
surface.
Bend out and pull down the sides of the revision shaft.
The edge of the revisions shaft must be flush with the wall surface.
Remove cistern cover.
Remove and keep the threaded bolts from the cistern cover.
Dispose of cistern cover.
WC flush actuation 21 from 48