Table 1.
Descriptions of each type of Non-Functional Requirement (NFR) [11].
| Type | Description |
|---|---|
| Availability (A) | Describes how likely the system is accessible for a user at a given point in time. |
| Fault Tolerance (FT) | Degree to which a system, product or component operates as intended despite the presence of hardware or software faults. |
| Legal & Licensing (L) | Certificates or licenses that the system must have. |
| Look & Feel (LF) | Describe the style of the product’s appearance. |
| Maintainability (MN) | Degree of effectiveness and efficiency with which a product or system can be modified by the intended maintainers. |
| Operability (O) | Degree to which a product or system has attributes that make it easy to operate and control. |
| Performance (PE) | Performance relative to the amount of resources used under stated conditions. |
| Portability (PO) | Degree of effectiveness and efficiency with which a system, product or component can be transferred from one hardware, software or other operational or usage environment to another. |
| Scalability (SC) | Degree to which a product or system can effectively and efficiently be adapted for different or evolving hardware, software or other operational or usage environments. |
| Security (SE) | Degree to which a product or system protects information and data, so that persons or other products or systems have the degree of data access appropriate to their types and levels of authorization. |
| Usability (US) | Degree to which a product or system can be used by specified users to achieve specified goals with effectiveness, efficiency, and satisfaction in a specified context of use. |