What other checklist questions can be asked to evaluate the adherence of an application to Standards? Some quality attributes standardized under ISO/IEC 9126 include 6 different qualities: Functionality, Reliability, Usability, Efficiency, Maintainability and Portability. The quality attributes tend to be in opposition to each other. Greater efficiency often negatively affects portability and maintainability. Portability will often limit the functionality of an application. Improve one quality attribute and another quality attributes might suffer. The trick then to being a good software architect is to make the tradeoffs necessary to deliver the proper solution for the system.