What is the definition of "Sequence Error Rate"?

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For example:
My calculation method is that if there are 5 pictures and 2 pictures have prediction errors, there are 3 wrong symbols in total.
My sequence error rate is 2/5=40%.
After reading the code, your method is 3/5=60%.

So the sequence error rate I got after training is 10.7%, which is a big difference from the paper.

So I want to ask which is the correct sequence error rate calculation.