The slides were presented at the re3data COREF / CoreTrustSeal Workshop on Data Quality Management at Repositories that took place on October 5, 2022, 12:00-15:30 UTC. The workshop featured perspectives on data quality assurance from research data repositories, the certification organization CoreTrustSeal, and the registry of research data repositories re3data. Presentations showcased measures research data repositories undertake to ensure data quality, with the objective to share experiences, raise awareness and make the various activities repositories perform to assure, assess, and improve data quality visible. These slides focus on the issues of data quality from the perspective of the CoreTrustSeal Requirements and Certification Process.