Soccer's experiment with two extra linesman behind the goals is to continue for another two years and will be extended beyond Europe, the sport's rule-making body said on Tuesday.
The new system, backed by UEFA president Michel Platini, was used in this year's Europa League and the International Football Association Board (IFAB) said on Tuesday that, although there were positive aspects, it needed further testing.
It is the only significant proposal on the table at present to help referees after the IFAB ruled out the use of goal line technology at a meeting in February.
"There's a general consensus that the experiment to date has been extremely interesting and I think most will agree that the results have proved more favourable than negative," said IFAB member and Welsh FA chairman Jonathan Ford.
"That's why we've supported the idea that this can be extended and opened up."
Jonathan Hall, another IFAB member, added: "We've had the test in the Europa League and 205 games in total, a number of incidents were noted in those games, but 205 games in the context of all the football played is not enough.
"We haven't seen enough evidence to say it's the most fabulous idea in the world but there are positives in terms of the deterrent effect for behaviour in the penalty area.
He added: "We're conscious that there are five confederations and 150 national federations outside Europe and we wanted to give them the opportunity as well.
"I think we will learn more from the pilots over the next two seasons."
FIFA general secretary Jerome Valcke said that all six continental confederations and 208 national associations would be invited to use the experiment in any competition.
The only condition was that the five officials would have to be used throughout the whole of any given competition.
"You can't just say you will carry out this test in the final," Valcke told reporters.
"It has to be throughout a competition, not just a single game. It has to be from the first game to the final game."
Image: An additional linesman is seen near the goal at a Cyprus-Czech Republic under-19 championship qualifier soccer game in Larnaca.