Mercedes' hopes of delivering on its strong winter testing form have received a boost, with the FIA confirming ahead of the Australian Grand Prix that a radical wing concept the team has pioneered is fully legal.
The Brackley-based outfit stirred up interest from its rivals throughout pre-season testing with its W03 featuring its own version of a rear-wing F-duct concept - that some suspected was activated by vents being opened when the upper wing elements moves during DRS activation.
It is understood that rival teams queried the legality of such a system - which vents the air through the endplates and in to the main plane, to help stall the wing and boost straight-line speed - with the FIA.
However, despite the way the system effectively makes use of driver movement when he activates the DRS, the FIA has no doubts that it complies with the regulations.
When asked by AUTOSPORT to clarify the situation, the head of the FIA's F1 technical department Charlie Whiting said: "Some teams are questioning it on the basis that they thought F-ducts were banned. Well, F-ducts are not banned.
"At the end of 2010 everyone was using driver operated F-ducts and the regulations that were changed specifically banned the use of driver movement to influence the aerodynamic performance of the car - that got rid of that generation of so-called F-ducts.
"At the beginning of last year, with engineers being unable to unlearn things, they wanted to try and get the effect via different means, and they talked about opening and closing a duct by having interaction with the suspension. We said no, you cannot do that because that is not the primary purpose of the suspension system - which is to insulate the car from undulations in the road.
"There was then a lengthy discussion in the TWG at the beginning of last year about that, to make sure everyone was clear about it. It seems a couple of teams went away from that meeting with the impression that F-ducts were banned in general. Whatever an F-duct is. But they are not."
Whiting would not reveal further details of how the Mercedes system works, but said that he viewed it as completely passive.
"What it appears some teams are doing is that when the DRS is operated, it will allow air to pass into a duct and do other things," he explained.
"That is all I can say - you will probably have a pretty good idea of what it might be doing, and other teams will as well. But it is completely passive. There are no moving parts in it; it doesn't interact with any suspension. No steering, nothing. Therefore I cannot see a rule that prohibits it."