PCI-DSS stands for Payment Card Industry Data Security Standard, which is a set of security requirements for organizations that handle credit card data. It aims to protect cardholder data from unauthorized access, disclosure, or theft, both in transit and at rest. PCI-DSS covers various aspects of security, such as encryption, authentication, firewall, logging, monitoring, and incident response. If you are working with a large retail chain and have concerns about their customer data, you should use PCI-DSS as the regulatory compliance standard to govern this data. SOC 3, AES-256, and ISO 27001 are not specific to credit card data protection, although they may have some relevance to general security practices. References: [PCI-DSS], [SOC 3], [AES-256], [ISO 27001].