Rocket Validator looks for accesibility violations on your pages using the axe-core accessibility engine, hosted on our own servers and integrated into our web crawler. You don't need to buy an additional license, everything's already included in your Pro account at Rocket Validator.
WCAG: Best Practice: Page must have one main landmark
It is a best practice to ensure that there is only one main landmark to navigate to the primary content of the page and that if the page contains
iframeelements, each should either contain no landmarks, or just a single landmark.
Navigating a web page is far simpler for screen reader users if all of the content splits between one or more high-level sections. Content outside of these sections is difficult to find, and its purpose may be unclear.
HTML has historically lacked some key semantic markers, such as the ability to designate sections of the page as the header, navigation, main content, and footer. Using both HTML5 elements and ARIA landmarks in the same element is considered a best practice, but the future will favor HTML regions as browser support increases.