Brawn, Toyota, Williams - the diffuser controversy

The controversy surrounding the Brawn, Toyota and Williams diffusers (which will be considered by the FIA's International Court of Appeal on April 14) goes beyond their external shape and dimensions. More important is the fact that all three designs use a 'window' or hole (red arrow) to feed the diffuser. That hole is horizontal in the case of the Williams, vertical for the other two teams, and is located where the floor's step plane meets the reference plane (black arrow). Rivals' cars, such as Ferrari's on the right, feature no such hole at this point. This difference stems from the question of whether the diffuser's three channels can be considered as separate entities, or whether they must be considered as one (enclosed) whole. Given the wording of the regulations, one can argue a case either way, though the majority of teams apparently took the spirit of the rules to mean that all three channels must have the same height and length, with no holes to feed them.