GRP – Window sill thickness [mm] – thickness of the finished window sill measured vertically

SP – Window sill width [mm] – total length (with sideways hanging on the wall)

SW – Recess width [mm] – window opening light (left–right)

GP – Window sill depth [mm] – total depth (including projection beyond the wall)

GWL – Recess depth left[mm] – from the window frame to the wall face on the left side

GWP – Depth of the right recess [mm] – from the window frame to the face of the wall on the right side

PP – Area [m²] – calculated on the basis of SP × GP (for one window sill)