What are the three types of system activity in requirements specification?

Autonomous activity (system acts on its own), user interaction (system gives users an ability), and interface requirement (system connects to another system) — each has its own sentence template.

1. Autonomous system activity:

• System acts on its own
• Template: "THE SYSTEM SHALL/SHOULD/WILL/MAY <process verb>"
• Example: "The system SHALL send email notifications daily at 9 AM"

2. User interaction:

• System provides capability to users
• Template: "THE SYSTEM SHALL/SHOULD/WILL/MAY provide <whom?> with the ability to <process verb>"
• Example: "The system SHALL provide administrators with the ability to reset user passwords"

3. Interface requirement:

• System must be able to connect/communicate
• Template: "THE SYSTEM SHALL/SHOULD/WILL/MAY be able to <process verb>"
• Example: "The system SHALL be able to export data in CSV format"