Where is it stipulated that the application surcharge should be charged according to the pct text?

Paragraph 3 of Article 11 of the Patent Cooperation Treaty. According to the third paragraph of Article 11 of the Patent Cooperation Treaty, if the number of pages of an international application exceeds 3, the acceptance bureau may charge the applicant an application surcharge per page. The calculation method of the application surcharge is based on the pct text, that is, the number of pages in the published text of the international application.