Early airplanes were mostly single-aisle, with six seats in each row, namely, A, B, C, D, E and F. AF stands for window position, CD stands for aisle position, and BE is the middle position. The letters A-F form an international convention, and specific letters represent windows, aisles and middle seats. A/F stands for windows and C/D stands for aisles. In order to be in line with international standards, the high-speed rail has continued this tradition.
The seat numbers of the high-speed rail seat distribution map are arranged in turn from the end of the carriage 1 and expressed in Arabic numerals. Seat positions are represented by five letters: a, b, c, d and f.
For example, in the 3+2 seating arrangement, three seats are represented by A, B and C, which respectively represent window, middle and aisle positions, and two seats are represented by D and F, which respectively represent aisle and window positions.
2+2 seating arrangements (including second-class seats/dining car seats) are denoted by A, C, D and F respectively; 2+ 1 seating arrangement is indicated by a, c and f respectively.
The seating arrangement of 1+ 1 (including second-class seats/dining car seats) is indicated by a and f respectively.
That is, no matter what arrangement, A and F stand for window seats, B stands for middle positions, and C and D stand for aisle seats.