The green watermark on the back is all three Roman letters. Judging from the known "back green watermark", there are only three groups: (1) iii iv (134): as long as these three crowns are combined at will, they are genuine. (2) Sanliu (136): As long as these three crowns are randomly combined, they are authentic. (3) Xiii (03 1): This group is slightly different from the above, and it is also the most chaotic group. There are four crown numbers as "back green watermarks" and two crown numbers as back green watermarks, that is, except for I III X( 130) and I X III (103) crown numbers, all other serial transformations are "back green watermarks". As long as the genuine product conforms to the above crown number, you can see the empty star five-star watermark. It has a green corner on the back.

The way to see the watermark is to aim the plane of the paper money at the strong light. There are basically about six hollow five-star watermarks in the unpatterned blank space of paper money, two in the upper and lower parts, one in the left and right unpatterned blank spaces, and a hollow five-pointed star. Those not in the above-mentioned crown number should be green and watermark-free.

62 years back green 1 corner (with watermark): the main pattern is "combination of education and productive labor"; Because the main color on the back of the ticket is green, there are distributed hollow star watermarks, so it is commonly known as "back green watermark"; The steganography of back green watermark is the same as that of ordinary back green version without the word "Ren". Steganography has the letter "A" at the upper end between the sixth and seventh railings on the right side of the gate, "X" at the lower end and "J" at the upper left corner.