It sounds pretty straightforward, but it's taken a lot of thought by the FIA and the teams to finalise the procedure. Indeed, the last details were only agreed in a meeting at the Barcelona test, and then approved in last week's World Motor Sport Council meeting.

So how will it work?

Firstly, the regulations do not specify rain, but actually say, "If track conditions are considered unsuitable to start the race at the scheduled time the start of the formation lap may take place behind the safety car" - and it's worth noting that the word "may" is a late substitution for "will" in the earlier version.

Although there is unlikely to be any other reason for such a procedure than bad weather, it's worth recalling a Macau GP event when a major oil spill from a support race forced starter Charlie Whiting to set the F3 cars off behind the safety car.

As was previously the case with safety car starts, the rules explain how the FIA will tell us what's happening: "At the 10-minute signal its orange lights will be illuminated, this being the signal to the drivers that the formation lap will be started behind the safety car. At the same time this will be confirmed to all teams via the official messaging system."

Assuming that heavy rain is the reason why the cars head off behind the safety car, then as before, "the use of wet-weather tyres until the safety car returns to the pits is compulsory," and "a penalty under Article 38.3(d) will be imposed on any driver who does not use wet weather tyres whilst the safety car is on the track at such times."

The procedure that the cars then follow is unchanged, with the addition the final line noted here: "When the green lights are illuminated the safety car will leave the grid and all drivers must follow in grid order, no more than 10 car lengths apart, and must respect the pitlane speed limit until they pass pole position. The safety car will continue until conditions are considered suitable for racing."

The key thing to remember is that any laps behind the safety car are not part of the race, and are in fact extra formation laps – in contrast to the previous procedure, when the race officially started once the safety car pulled away from the grid.

Pitlane starters

As a consequence of that, a major change from the past procedure is that cars starting from the pitlane due to a penalty or a strategic choice do not simply join the queue and start with the others.

Those drivers are allowed out once the cars on the grid have set off, and this will enable them to both get a feel for the wet track, and contribute to shifting standing water.

But when the time comes for the standing start, they have to peel into the pitlane and take the start from there. In other words, they don't get a free pass for any penalty, as was previously the case.

The rules explain it thus: "Any cars that were starting the race from the pitlane may join the formation lap once the whole field has passed the end of the pitlane for the first time. Any such cars may complete all formation laps but must enter the pitlane after the safety car returns to the pits and start the race from the end of the pitlane in the order they get there."

Furthermore, those drivers cannot follow the safety car into the pits and switch to intermediates or slicks for the start proper, or they will face a subsequent 10 second stop-and-go: "A penalty under Article 38.3(d) will be imposed on any driver who enters the pitlane under these circumstances and whose tyre(s) are changed for a different specification before leaving the pitlane."

One slight anomaly here is that drivers set to start from the pitlane are not obliged to do those formation laps, and thus when the race starts they could have a lot more fuel on board than those who did the formation laps and started from the grid.

There could be circumstances where that might be an advantage, but the consensus among teams when the rules were written was that the extra fuel would simply be a weight handicap rather than a benefit, and there was more to be gained by having the drivers get a feel for the wet.

Aside from those already committed to a pitlane start, any driver who starts from the grid behind the safety car, and then makes a pitstop during the formation laps, will also have to start from the pitlane.

In this respect, it's like a normal single formation lap – if you come in, you forfeit your chance to start from the grid - although in this case you can go back out on the track and complete more formation laps, as long as you return to the pitlane for the start proper, when the safety car comes in.

"Any other car entering the pitlane during the formation laps may re-join the track but must enter the pitlane after the safety car returns to the pits and start the race from the end of the pitlane in the order they get there."

In essence, this is to discourage drivers from trying to gain an advantage by switching to heated and fresh wet tyres just before the start, and rejoining the grid.

A driver at the back of the queue with little lose might still opt to make that choice of going to fresh wet tyres, and accept the pitlane start – but if he changes spec to inters or slicks, he too will get a 10-second stop-and-go.

In other words, nobody can change from full wets to another tyre of tyre without penalty until the end of the first racing lap.

No overtaking

Of course overtaking is not allowed when the cars are running behind the safety car, unless a car in front has some kind of problem, for example: "a) If a car is delayed when leaving the grid and cars behind cannot avoid passing it without unduly delaying the remainder of the field, or b) If there is more than one car starting from the pitlane and one of them is unduly delayed."

If a delayed driver cannot resume his original position before the standing start, he has to go to the pits and start from there.

The rules note that: "In either case drivers may only overtake to re-establish the original starting order or the order the cars at the pit exit were in when the formation lap was started.

"Any driver delayed in either way, and who is unable to re-establish the original starting order before he reaches the first safety car line on the lap the safety car returns to the pits, must enter the pitlane and may only join the race once the whole field has passed the end of the pitlane after the start of the race."

A driver who doesn't get back into the right place in the queue, but still goes to the grid and in effect messes up the procedure, will get a 10-second stop-and-go: "Any driver who fails to enter the pitlane if he has not re-established the original starting order before he reaches the first safety car line."

When the safety car is eventually called in, drivers simply head to their grid positions, and follow the pattern for a normal start.

"Once the safety car has entered the pitlane all cars, with the exception of those required to start from the pitlane, must return to the grid, take up their grid positions and follow the procedures set out in Article 36.9 to 36.13."

Originally, the rules were to impose a penalty on any cars that pitted during the formation laps, but as noted, that has changed, and those cars now have to start from the pitlane.

Of course, there is always a possibility that conditions do not improve while the formation laps are being run, in which case the race director reserves the right to bring the safety car and the queue back into the pitlane, and wait for a break in the weather. This is not officially a suspension, as the race hasn't actually started.

No second chance

However, it's clear from the rules that if this happens there will not be a second attempt at a standing start – in other words when the action does resume behind the safety car, that will be the start of the race, and the cars will eventually be released as was the case in the past.

The rules state: "If, after several formation laps behind the safety car, track conditions are considered unsuitable to start the race, the message "START PROCEDURE SUSPENDED" will be sent to all teams via the official messaging system and all cars must enter the pitlane behind the safety car. The procedures described in Articles 41 and 42 must then be followed and there will be no standing start."

If we get a standing start, or even if the attempt at a standing start is abandoned and we have a safety car start after a break, one key outcome will be how long the ensuing race is.

As mentioned, those laps behind the safety car count as formation laps. The simple formula for determining the length of the actual race is specified thus: "If the formation lap is started behind the safety car (see Article 39.16) the number of race laps will be reduced by the number of laps carried out by the safety car minus one."

In other words five formation laps will reduce a scheduled 70 lap race to 66, for example (70 minus five plus one). That's to take into account fuel loads, and the fact that for a normal dry race teams have to allow for a single formation lap when fuelling the cars.

It remains to be seen when we get our first chance to see how this new procedure unfolds, but one thing is clear: it has to be better for all concerned than what we've had in recent years.

Even in the dry starts are now more random than they used to be, and with full wet tyres on a wet track, an element of luck will be involved.

It will also be interesting to see the lines drivers take on the formation laps, because logic suggests that those starting on the racing line side of the grid will stick to it on the pit straight, and those starting on the other side will do their best to dry that part out, in an attempt to even up the odds.

When a wet standing start does finally happen the big question will be how soon will everyone head to the pits to offload those tyres, given that by definition conditions will be improving when the start takes place?

There's nothing in the rules to stop all 20 cars heading into the pits at the end of the first flying lap...