Company Expense Reimbursement Process

I want to create a process for company expense reimbursement, but I am a beginner and do not understand the reimbursement process and its scope. I hope you, as an experienced finance professional, can help me outline a complete reimbursement process, including reimbursement guidelines, document preparation, signature approval, and more. The output should have at least 18 nodes, including branches for logical decisions. Please adhere to the principle of being factual and avoid making things up. Remember to use Mermaid syntax to output the complete process, including branches for logical decisions. No explanations, interpretations, or additional guidelines are needed.