Why are there red and blue license plates?

B-type civilian vehicle, the license plate is red and white. Small civilian car, license plate with medium green background and white characters. Special vehicle for public security, with red "GA" in black on white background. Special vehicle for armed police, license plate with red letter "WJ" on white background. Military vehicle, license plate with white background, red Chinese characters: "A, B, C ..." Black character. The license plates of foreign cars in the embassy are black and white hollow "ambassador" signs. Foreign cars in the consulate, the license plate is ink-based, white and hollow "collar" signs. For other foreign cars, the license plate is white on a black background. The test license plate is written in white on a blue background with the word "try" written in front of the number. The license plate of the student car is white on a blue background, and the number is marked with the word "Xue". The temporary license plate is in red letters on a white background with the word "temporary" in front of the number. Car license plate, black letters on white background. The vehicle "mobile card" is red on a white background. There are two lines on the license plate of a civilian car. The top line of fine print is the name of the province, municipality directly under the central government and autonomous region and the special car for issuing armed police. The license plate is black with scarlet letters on a white background. Military vehicle, license plate with red letters on white background: "A, B, C ..." Black; The foreign car of the embassy, the license plate is white on a black background, and the hollow "ambassador" sign; Large civilian vehicles, license plates with white characters on red background; Small civilian car with white characters on green background in the middle of the license plate; For other foreign cars, the license plate is white on a black background; The test number plate is white on a blue background with the word "try" in front of it; The learning license plate is white on a blue background with the word "Xue" in front of the number; The temporary license plate is in red on a white background with the word "temporary" in front of the number; Vehicle replacement license plate, black and white; There are two lines on the license plate of a civil car. The fine print on the top line is the name of the province, municipality directly under the central government and autonomous region, and the code of the issuing agency and the regulatory agency, with the number from 01-99; Civil car number, generally 5 digits, that is, from 00001-99999; When the number exceeds 10, use English letters such as ABC instead, that is, A stands for 65438+ million, B stands for 1 1000, C stands for 12000, and the last letter Z stands for 330000; Avoid using I and O in English letters to avoid confusion with 1 and 0 (zero) in numbers.