As the Heineken Cup quarter-finals approach, the eight remaining clubs have the opportunity to strengthen their squads ahead of the knock-out stages.
Under tournament regulations the eight teams who win places in the Heineken Cup quarter-finals can register up to three additional players; two in any position and one front row forward.
This season clubs were also allowed introduce one Additional Player to their European squads during the Pool stages of the tournament, replacing one of the other registered players in the clubs 38 man European squad.
If a club introduced an Additional Player after Round 4 they would then be entitled to register only two Addtional Players to their squads for the knock-out stages.
Llanelli Scarlets is the only quarter-finalist club that did not nominate an Additional Player during the Pool stages. The other seven quarter-finalists brought in an Additional Player prior to Round 4.
Therefore, all eight Heineken Cup quarter-finalists are entitled to nominate three Additional Players for registration in their European squad.
To be eligible an additional player cannot have been named in the match-day squad for any other team this season in the European Challenge Cup or the Heineken Cup tournaments.
All clubs must submit their nominations on or before the Second Registration deadline of Thursday, 15 March 2007.