page 15 of 3rd Edition Revised, Rule 03.06.02.2 states in part:
"In campaign games, each empire may make one roll VS RM to transit a specific warp point once every 6 months. If the roll is successful, then the simultaneous transit must occur within the next 3 days."
It goes on to state that in referred games a player-race may plead their case for a simultaneous transit to the Space Master, but that the Space Master should be very hard to convince.
The above is correct. This was the subject of an extended debate on the Starfire list, which I am sad to say I wasted quite a bit of my life on. I had raised the subject of simul-transits (ST). I basically felt that in spite of the way the rules portrayed them, they were likely a less bloody way to assault a warp point, and therefore any sane and reasonable race would use them as a matter of course if they knew the other side had heavily fortified the far side of the warp point.
Some of you here may remember this weeks long debate. A particular individual on the list, who shall remain nameless, took the opposing side, and off we went. The debate lasted for weeks and descended into idiocy, IMO. The enitre subject ended up being one of the off-limits subjects for the list, along with the economic viability of O1 planets and several other subjects, not because of the potential for a flame-war, but because the stupidity that ensued was painful.
At any rate, ST's, in my opinion as someone that has used quite a few, can be a useful tactic. My own personal opinion is that any sane race would have to roll against RM, or possibly against RD, to determine if they would make a NORMAL assault against a heavily defended warp point, much less an ST attack, but that's just me.
Of course, there are some shifty defenses against an ST, especially if you have space (systems) to give up to the enemy in exchange for bleeding them dry, so an ST is definitely not THE tactic for all situations.
Kurt