diff --git a/syndicate/HOWITWORKS.md b/syndicate/HOWITWORKS.md
index 6b637f5..871966a 100644
--- a/syndicate/HOWITWORKS.md
+++ b/syndicate/HOWITWORKS.md
@@ -187,7 +187,7 @@ functions and caches of currently-asserted values.
            Index = Bag(V) × Node
             Node = Continuation × (Selector ⟼ Class ⟼ Node)
         Selector = 𝐍 × 𝐍		-- pop-count and index
-           Class = X × 𝐍		-- label and arity
+           Class = X			-- label
 
     Continuation = 𝒫(V) × ([H] ⟼ [V] ⟼ Leaf)
             Leaf = 𝒫(V) × ([H] ⟼ Handler)
@@ -253,12 +253,11 @@ cases where handlers are dynamically installed.
     projectMany v [h_0, ...] = [project v h_0, ...]
 
 **Definition.** The `classof` function extracts the constructor label
-  `x` and its arity `i` from a value `v`, yielding `()` if `v` is not
-  a record.
+  `x` from a value `v`, yielding `()` if `v` is not a record.
 
     classof :: V -> 1 + Class
     classof a                = ()
-    classof x(v_0, ..., v_i) = (x,i)
+    classof x(v_0, ..., v_i) = x
 
 **Definition.** The `extend` procedure augments an index with shape
   information `s`, by imperatively updating the index structure. It
@@ -286,7 +285,7 @@ cases where handlers are dynamically installed.
         walk-node h node n_pop n_index x(s_0, ... s_i) =
           let (cont, edges) = node
           let selector = (n_pop,n_index)
-          let class = (x,i)
+          let class = x
           if selector not in edges then
               edges[selector] := {}
           let table = edges[selector]