Theoretically, it is also effective to affix a private seal. But the personal seal and the official seal of the unit are different. The official seal of the unit is filed. If the other party does not recognize the authenticity of the official seal, it can be inspected and appraised. Article 197 Form and Main Clauses of Contract A loan contract shall be in written form, unless otherwise agreed between natural persons. The contents of the loan contract include the loan type, currency, purpose, amount, interest rate, term and repayment method.