Northern Ireland manager Nigel Worthington has indicated he would prefer to see goal-line technology introduced rather than two extra linesmen being employed.
UEFA president Michel Platini is attending a pilot scheme in Slovenia during an Under-19 qualifying tournament.
Two additional linesman will be placed behind the goalline to concentrate on incidents which occur in the penalty area.
Worthington, whose side face Slovenia tomorrow in a World Cup qualifier, said: ''I am not sure if the fourth official would still be in place but I cannot see how you would need six people to officiate a game.
''With the goings on in certain games, goal-line technology is something they should perhaps be looking into.
''However this new scheme is no doubt about trial and error and they (UEFA) will see what is right.''
The experiment with five match officials was approved at a meeting of the game's lawmakers, the International Football Association Board, in Scotland in March.
A separate proposal to experiment with goal-line technology was discussed at the same meeting but put on hold.
The event in Slovenia makes up the group five qualifiers for the championship and features the host nation, Norway, Slovakia and Armenia.
It begins today and runs until Wednesday with Platini taking in tomorrow's qualifier.
Further trials are planned for groups one and seven, in Hungary and Cyprus, later this year.