Add route change as the definition of page in spa

src/_accessibility/focus-management.md

@@ -58,7 +58,7 @@ On most static pages, you won’t need to move focus because browsers handle tha
 #### When a new page loads
 
 * **Don't move focus when a static page loads.** Browsers automatically set focus at the top, which works well for most users.
-* **For single-page applications, set focus to the first unique heading when a new page loads.** If the new content does not have a unique heading, choose the element that gives users the most context. For multi-page forms, follow the specific guidance for [managing focus in form flows]({{ site.baseurl }}/templates/forms/accessibility-guidelines#managing-focus-in-form-flows).
+* **For single-page applications, set focus to the first unique heading when a new page (route change) loads.** If the new content does not have a unique heading, choose the element that gives users the most context. In single-page applications, a new page is defined by a route change, even though the browser does not reload the document. For multi-page forms, follow the specific guidance for [managing focus in form flows]({{ site.baseurl }}/templates/forms/accessibility-guidelines#managing-focus-in-form-flows). 
 
 #### When page content is added or removed
 

src/_templates/forms/accessibility-guidelines.md

@@ -58,12 +58,12 @@ Digitized forms on VA.gov are built as single-page applications (SPAs). When use
 
 {% include a11y/focus-management-benefits-risks.md %}
 
-### Where to move focus when a new form page loads
+### Where to move focus when a new form page (route) loads
 
-When a new page loads in a form application, move focus to an element that gives users context and helps them find the next action. Use these guidelines to choose the best focus location:
+When a new page (or route) loads in a form application, move focus to an element that gives users context and helps them find the next action. Use these guidelines to choose the best focus location:
 
-- **If the page has a unique page heading**, set focus there. The unique heading is usually an H1 at the top of the page or H3 inside the step content.
-- **If the page does not have a unique page heading**, set focus on the step indicator header. This header is usually an H2.
+- **If the page has a unique page heading**, set focus there. The unique heading is usually an H1 at the top of the page or an H3 inside the step content. Each route should have a heading that is unique to that view.
+- **If the page does not have a unique page heading**, set focus on the step indicator header. This header is usually an H2. Avoid relying on this pattern when possible—prefer providing a unique heading for each route.
 - **When users navigate back to a form page**, treat it like a fresh page load and move focus to the top unique heading.
 
 ### Where to move focus in other scenarios