The recommendation to remove the player can be made by either the referee, the independent matchday doctor or the team doctor from the player's team.
Once that command is made, the referee will indicate that the player is leaving the field of play with a hand signal where he touches his head three times.
Once the player has been removed from the field of play and temporarily replaced, the team and independent match doctors will proceed through an IRB pitchside concussion assessment procedure incorporating standardised questions and observations.
If the player fails any aspect of the assessment and has relevant symptoms, he will not be able to return to the field of play and the substitution becomes permanent.
IRB Chief Medical Officer Martin Raftery said: "The safety and welfare of our players is of paramount importance for the IRB and its 118 member Unions.
"As a sport, we have been driving forward concussion management development and best-practice policy over the past decade but we can always do more to protect our athletes.
"The five-minute window is ample time and will deter tactical manipulation and will not impact on the shape and character of the game."
He added: "It is important to remember that these trials are not a fait acompli and we will undertake a thorough analysis of the results at the end of the IRB Junior World Championship and IRB Junior World Rugby Trophy.
"I would like to thank all the participating Unions and their doctors for their commitment and enthusiasm for this trial."
The IRB has been at the forefront of driving forward sport concussion research, policies and guidelines in recent years.
In 2011 the IRB introduced revised protocols governing concussion evaluation and 'Graduated Return to Play' guidelines. It also launched a fully interactive concussion management education website for players, coaches and doctors.
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