A3 paper refers to the international standard A3 paper with the size of 297mm×420mm and A4 paper with the size of 2 10mm× 297mm. A3 paper is twice as long as A4 paper. According to the basic area of paper format, the format specifications are divided into A series, B series and C series. A0 has a folio size of 841mm×1189mm and a folio area of 1m2. B0 has a width of1000 mm×1414 mm and a width area of1.5m2; C0 has a width of 9 17mm× 1279mm and a width area of/kloc-0.