Describe the scope. What is in scope? All factors not relevant SHOULD be left out.
Describe the business principles. You can use the tool within this playbook to get some inspiration.
Describe all stakeholders involved. Note the difference between stakeholders and actors!
Drivers for change
Business products and services
Business Information Model
Business Architecture Building Blocks
Describe mismatch between business baseline and target situation. Planning and transition plan is usually descripted in a project plan, not in a business architecture document.
Basic business architecture template