My understanding is that Andres is entirely right - the database for the Backroom is too big to implement a search of any sensible function.
There is the practical side effect that means most people can change their position without being exposed (apart from dedicated chaps like Lemur finding one out - and no-one believes him anyway). As in most parliaments, this provides plausible deniability and maintains the tradition that no-one ever changes their mind in the Backroom.
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