1. 6 '-ilities' further divided into sub-characteristics
   1. Functionality
      1. Suitability
      2. Accuracy
      3. Interoperability
      4. Compliance
      5. Security
   2. Reliability
      1. Maturity
      2. Recoverability
      3. Fault Tolerance
   3. Usability
      1. Learnability
      2. Understandability
      3. Operability
   4. Efficiency
      1. Time Behaviour
      2. Resource Behaviour
   5. Maintainability
      1. Stability
      2. Analyzability
      3. Changeability
      4. Testability
   6. Portability
      1. Installability
      2. Replaceability
      3. Adaptability
      4. Conformance
   7. Each quality sub-characteristic (e.g. adaptability) is further divided into attributes
      1. Attributes are not defined in the standard, as they vary between different software products.