In the chemical and biotech sector, China's State Intellectual Property Office (SIPO) and courts have been extremely strict when it comes to accepting supplementation of post-filing data during prosecution, invalidation or administrative litigation proceedings. The amended Patent Examination Guideline, which took effect on April 1 2017 seemed to provide some principles for the data supplementation issue. According to this, experimental data submitted after the filing date shall be analysed by the examiners. The technical effects to be testified by the supplemented experimental data should be such that a person skilled in the art can derive from the disclosure of the patent application. However, from such wording, it is still unclear to the applicant or patentee what the technical effect derivable from the disclosure of the patent application means exactly.