Before and after correction refer to the parts of the application that need to be corrected. For the content before correction, just fill in the problematic part written in the correction notice, or copy the original text. The modified content is the modified content, and it is ok to copy the original text, but it is best to add appropriate explanations. It doesn't matter if you don't save it, just have an electronic version of the application. Without it, you can't write your own application.
The process of correction is to submit the correction book and the modified application document replacement page at the same time.