What is an Independent Review of a Doctoral Dissertation?

According to Clause 1, Article 15 of the Regulation on Enrollment and Training at Doctoral Level issued together with Circular 18/2021/TT-BGDDT (Effective from August 15, 2021), regarding independent thesis review, specifically:

Independent Review is a mandatory process before the doctoral candidate's thesis can be defended before the Thesis Evaluation Council of the training institution. No later than 06 months from the time the doctoral candidate completes the thesis submission procedures after being approved by the relevant academic unit, the training institution must complete the independent review process for the doctoral candidate; in the case where a second independent review is required in accordance with Clause 3 of this Article, the period may be extended by a maximum of 03 months.

Respectfully,