Miele KM 6388 Operating And Installation Instructions page 54

Safety distances
Safety distance when installing the appliance near a wall with
additional niche cladding
A minimum safety distance must be maintained between the worktop cut-out and
any niche cladding to protect it from heat damage.
A minimum distance  of 50 mm between the worktop cut-out and the niche
cladding has to be maintained, if the cladding is made of flammable material (e.g.
wood).
If the niche cladding is made from a non-combustible material (e.g. metal, natural
stone, ceramic tiles) the minimum safety distance  between the cut-out and the
cladding may be 50 mm less the thickness of the cladding.
Example: 15 mm non-combustible niche cladding
50 mm - 15 mm = minimum safety distance of 35 mm
Flush-fitted cooktops
a Wall
b Niche cladding dimension x = thickness of the niche cladding material
c Worktop
d Worktop cut-out
e Minimum distance to
combustible materials 50 mm
non-combustible materials 50 mm - dimension x
54
Cooktops with frame or bevelled
edge