Bingbin Lu has an interesting short paper (9 pages only) on the best mode disclosure for patent applications. The author is answering two questions: whether a developing country should implement the best mode disclosure requirement and if so, how to best implement it?
Although the best mode disclosure requirement is optional for WTO member states in article 29 (1) TRIPs, Lu comes to the conclusion that developing countries need it. According to Lu it should be disclosed in the best mode known to the inventor, (which is in my subjective perception quite subjective) and Lu argues that a refusal to disclose this best mode must be a reason to refuse the grant of patent.
China's best mode disclosure requirement is called "preferred/optimally selected or specified mode for use" disclosure requirement in Rule 18 (5) of the Implementing Regulation of the Patent Law.
As Lu asserts Rule 18 is not a part of the Patent Law and therefore it cannot be a reason for refusal of a patent grant. According to Lu the State Intellectual Property Organisation (SIPO) has never enforced a preferred disclosure requirement in invalidation or appeal cases. Then again Lu explored the question whether developing countries should implement the best mode disclosure. The question is whether China can be easily labelled as a developing country or a developed country. China is both. To label China on a province level might be more meaningful.
Read Lu's paper here (pdf).