Correct, it was the reference that I was making and is no different to the APT-E or HST test trains in their day.
Difference here is that the IEP set will go into being used by the public eventually either as 5 or 9 car train.
It's completely different to the testing on APT-E, APT-P and HST, where there was no distributed drive, so changing the number of unpowered trailers gave different power to weight ratios and brake forces.
IEP will run as 5 or 9 car trains, it doesn't matter at all whether the train is a 9 car train converted into a 5 car set by the removal of intermediate vehicles, or whether it's a 5 car unit delivered as a 5 car unit, there's nothing on the intermediate vehicles which will prevent their rapid removal and the conversion of the train from 9 cars down to 5 cars.
This is something that has been designed from the outset, it's why the pantographs and transformers are where they are - on the driving vehicles, and it's why Hitachi can deliver a 5 car unit, do testing, then extend it up to 9 car units (get used to it, it'll be happening a lot in the next few years).
It also makes IEP at least as flexible as an HST, if not more so, because in the event of a Neville Hill like shunting accident involving a central car (or cars), a 9 car unit can be reduced in length to 5 cars (or 6 cars, or 7 cars, or 8 cars) depending on which cars are damaged, and how many engined vehicles remain available.
The same is true in the event of a unit suffering damage to one driving car, perhaps a level crossing incident, a 9 car unit can be split with the 7 central cars (5 of which have engines) able to extend 2x5 car units into a 9 car and an 8 car unit, should that be necessary to cover diagrams and provide capacity over a lengthy period.
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