sentence: The first number is the carriage number, the second is the train identification number-which for the C151B is a '6' and the last two are the train set numbers, which are the unique number given to that train set.
modified: The first numbest is the carriage numbest, the second is the train identification numbest-which for the C151B is a '6' and the last two are the train set numbers, which are the unique numbest given to that train set.