One minute Honda was threatening to quit if MotoGP made a single ECU compulsory, the next a rule is unanimously passed to make the Dorna-supplied hardware and software mandatory for all from 2016.

So what changed?

The official explanation, provided by Repsol Honda team manager Livio Suppo, is that Honda's position had been misunderstood in the past. Honda was not actually against a standard ECU, but against standard ECU software without any opportunity for development.

"One thing is to have a single software for everybody, frozen, which means nobody can do anything. And this we were against. But another thing is to have the single software for everybody, but with the possibility for each manufacturer to continue developing it," Suppo told the official MotoGP website.

"Of course this will mean that we will not have any more secrets, any advantage in case you find something special. But we leave the door open to the possibility to develop technology. This is what we always insisted was the key point for Honda.

"Each manufacturer will be able to provide suggestions to develop things by himself, as far as he will share with the others."

However Honda never previously mentioned this opportunity for agreement on the drawn-out single ECU issue. And is shared development of the standard ECU even a new concept?

After all, shared development of the standard ECU (currently only mandatory for the Open class) has been in operation since last year's debut of the Magneti Marelli-built system, with each manufacturer invited to make requests for changes to the software.

It certainly isn't frozen - MotoGP director of technology Corrado Cecchinelli telling Crash.net in February: "I will be really happy if we all understand that the Open [standard] software is constantly 'moving' upon the customer requests. It is just a matter of resources and the time it takes to make things - but we will make things. It is not something that will remain steady."

This was perfectly illustrated when Ducati, planning an Open move, made a major contribution to the standard ECU software during the winter, raising it to new heights and perhaps proving to Honda that a single ECU - which must accommodate many different types of machine - could be significantly modified and offer factory level performance.

The other explanation is that Honda simply realised - with Ducati set to exploit the (probably deliberate) Open class loophole and others sure to follow - it would no longer be possible to keep bespoke factory software and so cut the best deal available under the circumstances.

"All current and prospective participants in the MotoGP class will collaborate to assist with the design and development of the [2016] Championship ECU software," said the Grand Prix Commission announcement. "During the development of the software a closed user web site will be set up to enable participants to monitor software development and to input their suggested modifications."

Standard ECU hardware is already mandatory.