To limit the probability that the connection of yoke vents by means of an inappropriate fitting or at an inappropriate location will lead to the accumulation of sewage in yoke vents, which could lead to a reduced vent capacity, which could lead to siphonic action or back pressure in drainage systems, which could lead to trap seal failure, which could lead to the entry of sewer gases into occupied space, which could lead to negative effects on indoor air quality, which could lead to harm to persons.