What security standard pertains to the rules governing payment applications on POS devices?

The Payment Application Data Security Standard (PA-DSS) specifically addresses the security requirements for payment applications that are used in conjunction with Point of Sale (POS) devices. This standard was established to ensure that payment applications are designed in a manner that secures cardholder data and reduces vulnerabilities associated with the processing of payment transactions.

The PA-DSS guidelines require that applications support PCI DSS compliance for the merchants who use them. Thus, any payment application must adhere to secure coding practices, ensure proper encryption of cardholder data, and maintain transactional integrity. By complying with PA-DSS, software vendors help protect consumers' sensitive payment information and prevent data breaches during card payment transactions.

In contrast, while PCI DSS (Payment Card Industry Data Security Standard) encompasses broader security requirements that apply to all entities involved in payment processing, it does not specifically govern the design and functionality of the applications used on POS devices. ISO 27001 is a standard for information security management systems and is not limited to payment applications, while HIPAA pertains to patient health information privacy and is unrelated to payment processing standards.