Miele DGC 6805 Operating And Installation Instructions page 171

Cut-outs for ventilation and plumbing hoses
To ensure the appliance has adequate ventilation and room for the inlet and drain
hoses, the following cut-outs measuring 500 x 40 mm must be provided:
in the top of the housing unit (for ventilation)
in the interim shelf above the building-in niche (for ventilation)
in the base of the building-in niche (for inlet and drain hoses)
in the base of the housing unit (for inlet and drain hoses)
The furniture housing unit must not have a back panel fitted behind the building-in
niche.
Appliance and building-in dimensions
171