Quality control (QC) aims to identify errors in the final dataset, meaning that it occurs after all field decisions (good and bad) have taken place. During QC, the ability to correct errors is limited because points cannot be revisited with the exact conditions that occurred during the original data collection event.
If you have specific questions about QA/QC procedures please follow the guidelines outlined in the Monitoring Manual for Grassland, Shrubland, and Savanna Ecosystems Vol. I. Contact the national data team with questions.