top face perpendicular to wall

bottom face perpendicular to wall

both top and bottom faces perpendicular to wall

none of the above

(i) and (ii),

(ii) and (iii)

(i) and (iv)

(iii) and (iv)

not provided

provided only on inner face

provided only on front face

provided both on inner and front faces

only (i)

only (ii)

both (i) and (iv)

both (ii) and (iii)

front face only

inner face only

both front face and inner face

none of the above