--- title: "Document structure · Sitebulb Labs" description: "Landmarks and an unbroken heading order are how an agent builds a map of the page before acting on it." url: https://labs.sitebulb.com/docs/checks/agent-experience/ax-document-structure/ --- # Document structure Landmarks and an unbroken heading order are how an agent builds a map of the page before acting on it. - Category [Agent experience](https://labs.sitebulb.com/docs/checks/agent-experience) - Standard Recommended ## What it checks The extension reads the rendered page’s outline in your browser and looks for three problems: - **No `

`.** The page has no top-level heading. - **Skipped heading levels.** A heading jumps down more than one level, such as an `

` followed directly by an `

`. One skip is tolerated; two or more count as a problem. - **No `
` landmark.** Neither a `
` element nor `role="main"` is present. Headings are read from inside `
` when the page has one, so headings in the navigation, sidebar and footer do not count against the outline. Hidden elements are ignored. Multiple `

` elements are not flagged. ## Results | Status | When | | -------------- | --------------------------------------------------------------------------------- | | **Pass** | There is an `

`, at most one skipped level, and a `
` landmark | | **Warn** | There is an `

`, but levels are skipped more than once or there is no `
` | | **Fail** | The page has no `

` | | **Unmeasured** | The extension could not read the page (open it in the active tab) | When levels are skipped, the result lists each offending pair and the heading it follows. ## How to fix Wrap the primary content in `
`, give the page one `

`, and step heading levels down one at a time: ```html
…

Blue running shoes

Sizing

Wide fit

Care

…
``` An agent reads the outline as a tree. A jump from `

` to `

` makes a section look like the child of the wrong parent, and without `
` it cannot skip the navigation and footer to reach the content.