FIFA is hoping to be granted permission from the International Football Association Board (IFAB) to continue trials of Football Video Support (FVS), an alternative VAR system which gives coaches the chance to challenge decisions.

FVS, which was used at the U20 and U17 FIFA Women's World Cups this year, was approved for testing by the IFAB in March, and FIFA now wants to expand it to other competitions. It was first deployed during the Blue Stars/FIFA Youth Cup, a FIFA competition held in Zurich in May, before being used at the two international tournaments.

Rather than reviews being overseen and controlled only by an official acting as a video assistant referee, FVS gives coaches the chance to make up to two challenges per match if they feel an error has been made.

"We are at the beginning of the trial and the experiences at both the U20 and U17 FIFA Women's World Cup will be carefully analysed but so far, we haven't noticed anything unexpected," Pierluigi Collina, the chairman of FIFA's referees' committee, told ESPN.

"As agreed, FIFA will present a report at the next IFAB ABM and request to continue the trial on a wider basis. Several FIFA member associations already showed the interest to participate to the trial. If IFAB will give the permission, next year there will be several competitions using FVS."

At present, the challenge system is only intended for use in leagues with fewer resources, ideally with no more than four cameras, rather than top divisions like the Premier League.

"Making clear that FVS is not VAR is critical, in particular in terms of expectations," Collina said. "Because of the limited number of cameras, FVS won't be able to show what VAR can show. Offside is an example: without cameras properly positioned, only clear offside can be spotted. This makes the on-field decision important too.

"FVS is designed to work with a limited camera set up, ideally up to 4-5. With more cameras, the process of checking all of the footage and available angles may become very long as, and differently from VAR, there are not any video match officials selecting those clips to be seen by the referee."

With FVS the coach makes a challenge to a decision and the referee then goes to the side of the pitch to view a replay of the incident. Unlike with VAR, there is only a replay operator who cues up the video. The match referee alone then assesses his own decision and isn't told he has made a clear and obvious error in advance.

Collina added: "Even though [the U20 and U17 FIFA Women's World Cup] was the first experience, both for the teams and the match officials, we feel that the outcome was very positive. We ensured that they were well briefed beforehand and we conducted a survey with the coaches after the tournament which showed that FVS was positively received and considered worthy to be used in the future."

Collina said that the FVS challenge system places the responsibility solely on the coaches, and referees would not action reviews themselves.

"Coaches have a limited number of review requests, two per match, and they lose it when unsuccessful," Collina added. "Therefore, they are careful not to waste review requests during the match. It could happen that they make a sort of 'last try' for an incident that occurs at the very end of the match, but that wouldn't necessarily present a tactical advantage.

"Giving the referee the possibility to initiate a review would mean to put him/her under extra pressure, as players would try to convince the referee to decide to go to the monitor every time a decision is taken. For this reason coaches are responsible for the decision to request a review, though they could be recommended by players, as they are often closer to the incident, if not directly involved.

"Part of the FIFA president's vision is to explore both existing and emerging technologies to positively impact the game, especially in order to help referees to make correct decisions. We want to do this while ensuring that any potential use is cost-effective, beneficial and practical across the global football community.

"While VAR is used in some 200 competitions around the world, many others cannot implement it due to the limited financial and human resources available. Football Video Support is a more affordable technology that many more FIFA member association can implement to help referees when needed. VAR and FVS are different solutions for different needs."