Keerthan,
The document template for Functional specification format should be determined by the organization how they want it.
Also, Functional Specifications answers the Questions as:
1. What is the Type of requirement (from RICEF i.e., is it a Report or Enahncement or Form or Interface)
2. What is the exact requirement.
3. What are the tables and Fields involved.
4. What are the screens involved (if any).
5. What would be the selection screen (if report).
6. What would be the exact format.
7. What are the controls and authorization checks involved. etc.
Sharing hereby one sample document found on google as below but still it is how your organization wants to design it:
Hope this helps.
Regards,
Chin2.