Proper documentation of a cost element of a cost estimate would include?

Proper documentation of a cost element in a cost estimate should include a clear description of the cost item, including its purpose and relevance to the project. It should also specify the basis for the cost estimate, such as historical data, quotes, or industry standards, and provide detailed calculations or assumptions used to derive the cost. Additionally, any supporting documents, such as invoices or vendor agreements, should be referenced to ensure transparency and accuracy. Finally, it should outline any contingencies or risks associated with the cost element.