Question: Do all modifications to source data require a record of the reason for the modification? (GCP 2020 No. 57, Chapter 4) @ @ Yes. The modification of source data should leave a trace to understand what was before the modification and what was after the modification (which cannot conceal the initial data), and the reason for the modification needs to be explained. The implementation of electronic records is relatively simple (which can be used as a procedural requirement), but for paper records, it is a new requirement.