diff --git a/specification.md b/specification.md
index c3a71a1b..f3c5df08 100644
--- a/specification.md
+++ b/specification.md
@@ -550,15 +550,14 @@ Two actors minimum:
 
 You can optionally add:
 
-* **review_actor** (code review / QA)
 * **apply_actor** (release/merge specialist)
-  …but these can also be handled as subplans.
 
 Actors can be:
 
-* an LLM agent,
-* a graph,
-* or another actor reference.
+* an LLM agent (built-in),
+* a graph (custom yaml, or built-in),
+
+Note: graphs are hierarchical allowing them to reference other actors as nodes.
 
 Actor abstraction is central: an actor may be a single agent or an entire graph.