diff --git a/packages/router/src/router_module.ts b/packages/router/src/router_module.ts
index cd4372f97f..81bc596475 100644
--- a/packages/router/src/router_module.ts
+++ b/packages/router/src/router_module.ts
@@ -360,7 +360,15 @@ export interface ExtraOptions {
    * Defines how the router merges parameters, data, and resolved data from parent to child
    * routes. By default ('emptyOnly'), inherits parent parameters only for
    * path-less or component-less routes.
+   *
    * Set to 'always' to enable unconditional inheritance of parent parameters.
+   *
+   * Note that when dealing with matrix parameters, "parent" refers to the parent `Route`
+   * config which does not necessarily mean the "URL segment to the left". When the `Route` `path`
+   * contains multiple segments, the matrix parameters must appear on the last segment. For example,
+   * matrix parameters for `{path: 'a/b', component: MyComp}` should appear as `a/b;foo=bar` and not
+   * `a;foo=bar/b`.
+   *
    */
   paramsInheritanceStrategy?: 'emptyOnly'|'always';