The pool stages of the European Cup will be played on a home and away basis next season - rather than one-off games - with the number of teams from each country remaining the same. England, France and Wales will each have four representatives, Ireland and Scotland three each and Italy one.
The final place will be decided by a play-off between Italy's second nomination and Romania's champion club.
The 20 teams will be split into five pools of four with the winners of each going through to the quarter-finals. The remaining quarter-finalists will be drawn from three matches played between the five runners-up and the best third-placed team.
The format for the European Conference has yet to be decided, but matches will be played on some, or all, of the weekends devoted to European Cup games.
The Rugby Football Union have responded in a calm manner to criticism from Orrell's chairman, Ron Pimblett, that his club's amendments before the special general meeting on 9 March had not been circulated.
"This appears to be a blatant attempt by RFU committees to disenfranchise the membership and remove the democratic process," Pimblett said.
But the RFU denied the charges last night. "We would submit the RFU has acted efficiently and promptly," a statement said.
Orrell, supporters of the executive committee chairman, Cliff Brittle, want guaranteed powers for the chairman of the management board under the new structure.
The Swansea coach, Mike Ruddock, is considering a three-year contract with Leinster. Ruddock joined the Welsh club after a spell with Bective Rangers.Reuse content