Answer: A
Patent documents refer to documents written in accordance with the format requirements and content requirements stipulated by patent laws around the world, and specifically record specific technical solutions used to apply for patents. Theoretical discoveries are not the subject of patent law protection and therefore will not be recorded in patent documents. The main characteristics of patent documents are: ① Huge quantity and extensive content; ② Integrating technical, legal and economic information; ③ Spreading the latest scientific and technological information; ④ Uniform and standardized format.