I have seen the checklists and guidelines for web accessibility testing in the Internet. Also there is a Reporting tool which allows us to provide the observations as inputs and it generates the report.

I wanted to understand how the levels ( A / AA / AAA) are determined during the evaluations when one is using the W3C checklists as few of the pages would have achieved Level A and few of them would have achieved AA. In this case, how the overall levels are determined for the application.

Clarification would be of great help. Thanks!