Non-Functional

 Having a hard time thinking of nonfunctional requirements? Here are some categories and "trigger questions" that may help. ===User Interface & Human Factors === 
 * What type of user will be using the system?
 * Will more than one type of user be using the system?
 * What sort of training will be required for each type of user?
 * Is it particularly important that the system be easy to learn?
 * Is it particularly important that users be protected from making errors?
 * What sort of input/output devices for the human interface are available and what are their characteristics?

Documentation

 * What kind of documentation is required?
 * What audience is to be addressed by each document?

Hardware Considerations

 * What hardware is the proposed system to be used on?
 * What are the characteristics of the target hardware, including memory size and auxiliary storage space?

Performance Characteristics

 * Are there any speed, throughput, or response time constraints on the system?
 * Are there size or capacity constraints on the data to be processed by the system?
 * Error Handling and Extreme Conditions
 * How should the system respond to input errors?
 * How should the system respond to extreme conditions?

System Interfacing

 * Is input coming from systems outside the proposed system?
 * Is output going to systems outside the proposed system?
 * Are there restrictions on the format or medium that must be used for input or output?

Quality Issues

 * What are the requirements for reliability?
 * Must the system trap faults?
 * Is there a maximum acceptable time for restarting the system after a failure?
 * What is the acceptable system downtime per 24-hour period?
 * Is it important that the system be portable (able to move to different hardware or operating system environments)?

System Modifications

 * What parts of the system are likely candidates for later modification?
 * What sorts of modifications are expected?

Physical Environment

 * Where will the target equipment operate?
 * Will the target equipment be in one or several locations?
 * Will the environmental conditions in any way be out of the ordinary (for example, unusual temperatures, vibration, magnetic fields)?

<span style="background-color: transparent; color: #000000; font-family: Times New Roman; font-size: 16px; text-align: left; text-decoration: none; vertical-align: auto;">Security Issues
===<span style="background-color: transparent; color: #000000; font-family: Times New Roman; font-size: 16px; text-align: left; text-decoration: none; vertical-align: auto;">Resources and Management Issues ===
 * <span style="background-color: transparent; color: #000000; display: block; font-family: Times New Roman; font-size: 16px; text-align: left; text-decoration: none; vertical-align: auto;">Must access to any data or the system itself be controlled?
 * Is physical security an issue?
 * <span style="background-color: transparent; color: #000000; display: block; font-family: Times New Roman; font-size: 16px; text-align: left; text-decoration: none; vertical-align: auto;">How often will the system be backed up?
 * Who will be responsible for the back up?
 * Who is responsible for system installation?
 * Who will be responsible for system maintenance?