diff --git a/TODO.md b/TODO.md
index a7d51fae..52e90fc9 100644
--- a/TODO.md
+++ b/TODO.md
@@ -12,6 +12,10 @@
 
 no `defru` just `defrule` -- add feature when very very needed
 
+# bug
+
+why no active edge in `Nat.inet.four.initial`？
+
 # render
 
 `NetRenderer` -- format to simple text representation of graph
diff --git a/docs/notes/design-of-new-syntax.md b/docs/notes/design-of-new-syntax.md
index e9ca6b7b..0fc3a6c4 100644
--- a/docs/notes/design-of-new-syntax.md
+++ b/docs/notes/design-of-new-syntax.md
@@ -10,14 +10,14 @@ Use `defnode` to define a node.
 
 `--` separates input ports from output ports in the definition.
 
-Use `!` as prefix to mark the principle port.
+Use `!` as postfix to mark the principle port.
 
 ```inet
-defnode zero -- !return: Nat end
+defnode zero -- return: Nat! end
 
-defnode add1 prev: Nat -- !return: Nat end
+defnode add1 prev: Nat -- return: Nat! end
 
-defnode add !x: Nat y: Nat -- return: Nat end
+defnode add x: Nat! y: Nat -- return: Nat end
 ```
 
 If there is only one output port,
@@ -25,11 +25,11 @@ the `return` is the default name,
 thus can be omitted.
 
 ```inet
-defnode zero -- !Nat end
+defnode zero -- Nat! end
 
-defnode add1 prev: Nat -- !Nat end
+defnode add1 prev: Nat -- Nat! end
 
-defnode add !x: Nat y: Nat -- Nat end
+defnode add x: Nat! y: Nat -- Nat end
 ```
 
 Use `defrule` to define a rule,
@@ -74,18 +74,18 @@ end
 We use a simple type system like Haskell (for now).
 
 ```inet
-defnode sole -- !Trivial end
+defnode sole -- Trivial! end
 
-defnode null -- !List('a) end
+defnode null -- List('a)! end
 
 defnode cons
   head: List('a)
   tail: List('a)
-  -- !List('a)
+  -- List('a)!
 end
 
 defnode append
-  left: !List('a)
+  left: List('a)!
   right: List('a)
   -- List('a)
 end
@@ -122,17 +122,17 @@ end
 defnode diff
   left: List('a)
   right: List('a)
-  -- !DiffList('a)
+  -- DiffList('a)!
 end
 
 defnode diff_append
-  !left: DiffList('a)
+  left: DiffList('a)!
   right: DiffList('a)
   -- DiffList('a)
 end
 
 defnode diff_open
-  !DiffList('a)
+  DiffList('a)!
   list: List('a)
   -- List('a)
 end