diff --git a/aip/general/0136.md b/aip/general/0136.md
index 6ad317e09e..ef0481343e 100644
--- a/aip/general/0136.md
+++ b/aip/general/0136.md
@@ -100,8 +100,8 @@ rpc SortBooks(SortBooksRequest) returns (SortBooksResponse) {
 }
 ```
 
-- The collection's parent resource **must** be called `parent`, and
-  be the only variable in the URI path.
+- If the collection's resource has a parent, that resource **must** be called
+  `parent` and be the only variable in the URI path.
 - The collection key (`books` in the above example) **must** be literal.
 
 ### Stateless methods