Legal analysis: Requirements: 1. The judicial technicians of the people's court shall review the appraisal time of the entrusted case and the qualification of the appraisal institution, and require the submitting unit to provide a comparative sample if the time of signature and suspicion exceeds six months. 2, can't use the self-provided samples of appraisal institutions to document the appraisal time. Because the difference between the sample and the sample in paper and storage environment will affect the appraisal result.

legal basis: article 27 of the judicial authentication procedure of the people's Republic of China, the judicial appraiser shall record the authentication process in real time and sign it. Records can be made by taking notes, recording, video recording, taking photos, etc. Records shall specify the main identification methods and processes, inspection, inspection and test results, and the use of instruments and equipment. The recorded contents shall be true, objective, accurate, complete and clear, and the recorded text materials, audio-visual materials, etc. shall be stored in the appraisal files.