What is E231 series?
{{Infobox train | background = | name = | image = File:JR East E231-0 Series Mitsu B11 Inage.Sta.jpg | imagealt = | imagesize = 250px | caption = Chuo–Sobu Line E231-0 | interiorimage = | interiorimagealt = | interiorcaption = | service = 2000–now | manufacturer = | designer = | assembly = | ordernumber = | factory = | family = | replaced = | yearconstruction = | yearservice = | refurbishment = | yearscrapped = 2010–2011 (6 Door cars) | numberconstruction = | numberbuilt = 2,736 | numberservice = 2,476 (+48 converted) | numberpreserved = | numberscrapped = | predecessor = | successor = [[E235 series]] (Yamanote Line) | formation = | diagram = | code = | fleetnumbers = | capacity = | operator = | depots = | lines = | carbody = | trainlength = | carlength = | width = | height = | lowfloor = | floorheight = | platformheight = | entrylevelorstep = | doors = | art-sections = | wheeldiameter = | wheelbase = | maxspeed = | weight = | axleload = | steep gradient = | traction = | engine = | enginetype = | cylindercount = | cylindersize = | traction motors = | poweroutput = | tractiveeffort = | transmission = | acceleration = | deceleration = | aux = | powersupply = | hvac = | electricsystem = | collectionmethod = | uicclass = | aarwheels = | wheels driven = | bogies = | minimum curve = | brakes = | safety = | coupling = | multipleworking = | light = | gauge = 1,067mm | notes = }} The {{Nihongo|'''E231 series'''|E231系|E231-kei}} is an [[electric multiple unit