angular · Jul 11, 2024
diff --git a/‎src/cdk/a11y/BUILD.bazel
+1 b/‎src/cdk/a11y/BUILD.bazel
+1
diff --git a/‎src/cdk/a11y/a11y.md
+25-1 b/‎src/cdk/a11y/a11y.md
+25-1
@@ -19,6 +19,7 @@ ng_module(
     deps = [
         "//src:dev_mode_types",
         "//src/cdk/coercion",
+        "//src/cdk/coercion/private",
         "//src/cdk/keycodes",
         "//src/cdk/layout",
         "//src/cdk/observers",
 
@@ -27,7 +27,7 @@ Navigation through options can be made to wrap via the `withWrap` method
 this.keyManager = new FocusKeyManager(...).withWrap();
 ```
 
-#### Types of key managers
+#### Types of list key managers
 
 There are two varieties of `ListKeyManager`, `FocusKeyManager` and `ActiveDescendantKeyManager`.
 
@@ -55,6 +55,30 @@ interface Highlightable extends ListKeyManagerOption {
 
 Each item must also have an ID bound to the listbox's or menu's `aria-activedescendant`.
 
+### TreeKeyManager
+
+`TreeKeyManager` manages the active option in a tree view. Use this key manager for
+components that implement a `role="tree"` pattern.
+
+#### Basic usage
+
+Any component that uses a `TreeKeyManager` should do three things:
+* Create a `@ViewChildren` query for the tree items being managed.
+* Initialize the `TreeKeyManager`, passing in the options.
+* Forward keyboard events from the managed component to the `TreeKeyManager` via `onKeydown`.
+
+Each tree item should implement the [`TreeKeyManagerItem`](/cdk/a11y/api#TreeKeyManagerItem) interface.
+
+#### Focus management
+
+The `TreeKeyManager` will handle focusing the appropriate item on keyboard interactions.
+
+`tabindex` should also be set by the component when the active item changes. This can be listened to
+via the `change` property on the `TreeKeyManager`. In particular, the tree should only have a
+`tabindex` set if there is no active item, and should not have a `tabindex` set if there is an
+active item. Only the HTML node corresponding to the active item should have a `tabindex` set to
+`0`, with all other items set to `-1`.
+
 
 ### FocusTrap