21. The engagement to report on whether a previously reported material weakness continues to exist must be performed by a person or persons having adequate technical training and proficiency as an auditor. In all matters related to the assignment, an independence in mental attitude must be maintained. Due professional care must be exercised in the performance of the engagement and the preparation of the report. Paragraphs 30 through 36 of Auditing Standard No. 2 describe the application of these standards in the context of an internal control-related service.