I am going to start a little side project very soon, but this time i want to do not just the little UML domain model and case diagrams i often do before programming, i thought about making a full functional specification. Is there anybody that has experience writing functional specifications that could recommend me what i need to add to it? How would be the best way to start preparing it? Here i will write down the topics that i think are more relevant:

• Purpose
• Functional Overview
• Context Diagram
• Critical Project Success Factors
• Scope (In & Out)
• Assumptions
• Actors (Data Sources, System Actors)
• Use Case Diagram
• Process Flow Diagram
• Activity Diagram
• Security Requirements
• Performance Requirements
• Special Requirements
• Business Rules
• Domain Model (Data model)
• Flow Scenarios (Success, alternate…)
• Time Schedule (Task Management)
• Goals
• System Requirements
• Expected Expenses

What do you think about those topics? Shall i add something else? or maybe remove something?