diff --git a/TODO.md b/TODO.md
index 891f8601..324b6243 100644
--- a/TODO.md
+++ b/TODO.md
@@ -1,5 +1,3 @@
-[bug] why no active edge in `Nat.inet.four.initial`？
-
 `connect` v.s. `reconnect`
 
 - `reconnect` is used in `PortReconnect`
diff --git a/docs/tests/DiffList.inet b/docs/tests/DiffList.inet
index c94bbc7e..11c76786 100644
--- a/docs/tests/DiffList.inet
+++ b/docs/tests/DiffList.inet
@@ -1,23 +1,23 @@
-defnode sole -- return! end
+defnode sole -- value! end
 
-defnode null -- return! end
+defnode null -- value! end
 
 defnode cons
   head
   tail
   -------
-  return!
+  value!
 end
 
 defnode diff
   left
   right
   ------
-  return!
+  value!
 end
 
 defnode diff_append
-  left!
+  target!
   right
   ------
   return
@@ -30,7 +30,7 @@ defrule diff diff_append
 end
 
 defnode diff_open
-  diff_list!
+  target!
   list
   ------
   return
diff --git a/docs/tests/DiffList.inet.one_two_soles.finial.txt b/docs/tests/DiffList.inet.one_two_soles.finial.txt
index 5536acfd..690d3cdd 100644
--- a/docs/tests/DiffList.inet.one_two_soles.finial.txt
+++ b/docs/tests/DiffList.inet.one_two_soles.finial.txt
@@ -1,8 +1,8 @@
-(sole₁)-return head-(cons₂)
-(sole₅)-return head-(cons₆)
-(sole₇)-return head-(cons₈)
-(cons₆)-return tail-(cons₈)
+(sole₁)-value head-(cons₂)
+(sole₅)-value head-(cons₆)
+(sole₇)-value head-(cons₈)
+(cons₆)-value tail-(cons₈)
 (cons₆)-tail left-(diff₁₃)
-(cons₂)-return return-(cons₈)
+(cons₂)-value value-(cons₈)
 (cons₂)-tail right-(diff₁₃)
-(diff₁₃)-return
\ No newline at end of file
+(diff₁₃)-value
\ No newline at end of file
diff --git a/docs/tests/DiffList.inet.one_two_soles.initial.txt b/docs/tests/DiffList.inet.one_two_soles.initial.txt
index 0ce30ed1..e3ded944 100644
--- a/docs/tests/DiffList.inet.one_two_soles.initial.txt
+++ b/docs/tests/DiffList.inet.one_two_soles.initial.txt
@@ -1,11 +1,11 @@
-(diff₉)-return!left-(diff_append₁₀)
-(sole₁)-return head-(cons₂)
-(cons₂)-return left-(diff₃)
-(sole₅)-return head-(cons₆)
-(sole₇)-return head-(cons₈)
-(cons₆)-return tail-(cons₈)
-(cons₈)-return left-(diff₉)
-(diff₃)-return right-(diff_append₁₀)
+(diff₉)-value!target-(diff_append₁₀)
+(sole₁)-value head-(cons₂)
+(cons₂)-value left-(diff₃)
+(sole₅)-value head-(cons₆)
+(sole₇)-value head-(cons₈)
+(cons₆)-value tail-(cons₈)
+(cons₈)-value left-(diff₉)
+(diff₃)-value right-(diff_append₁₀)
 (diff₃)-right tail-(cons₂)
 (diff₉)-right tail-(cons₆)
 (diff_append₁₀)-return
\ No newline at end of file
diff --git a/docs/tests/DiffList.inet.two_two_soles.finial.txt b/docs/tests/DiffList.inet.two_two_soles.finial.txt
index a2325cb4..e58f5d88 100644
--- a/docs/tests/DiffList.inet.two_two_soles.finial.txt
+++ b/docs/tests/DiffList.inet.two_two_soles.finial.txt
@@ -1,10 +1,10 @@
-(sole₁₅)-return head-(cons₁₆)
-(sole₁₇)-return head-(cons₁₈)
-(cons₁₆)-return tail-(cons₁₈)
-(sole₂₁)-return head-(cons₂₂)
-(sole₂₃)-return head-(cons₂₄)
-(cons₂₂)-return tail-(cons₂₄)
+(sole₁₅)-value head-(cons₁₆)
+(sole₁₇)-value head-(cons₁₈)
+(cons₁₆)-value tail-(cons₁₈)
+(sole₂₁)-value head-(cons₂₂)
+(sole₂₃)-value head-(cons₂₄)
+(cons₂₂)-value tail-(cons₂₄)
 (cons₂₂)-tail left-(diff₂₉)
-(cons₁₈)-return return-(cons₂₄)
+(cons₁₈)-value value-(cons₂₄)
 (cons₁₆)-tail right-(diff₂₉)
-(diff₂₉)-return
\ No newline at end of file
+(diff₂₉)-value
\ No newline at end of file
diff --git a/docs/tests/DiffList.inet.two_two_soles.initial.txt b/docs/tests/DiffList.inet.two_two_soles.initial.txt
index 02e15d96..fc11d253 100644
--- a/docs/tests/DiffList.inet.two_two_soles.initial.txt
+++ b/docs/tests/DiffList.inet.two_two_soles.initial.txt
@@ -1,13 +1,13 @@
-(diff₂₅)-return!left-(diff_append₂₆)
-(sole₁₅)-return head-(cons₁₆)
-(sole₁₇)-return head-(cons₁₈)
-(cons₁₆)-return tail-(cons₁₈)
-(cons₁₈)-return left-(diff₁₉)
-(sole₂₁)-return head-(cons₂₂)
-(sole₂₃)-return head-(cons₂₄)
-(cons₂₂)-return tail-(cons₂₄)
-(cons₂₄)-return left-(diff₂₅)
-(diff₁₉)-return right-(diff_append₂₆)
+(diff₂₅)-value!target-(diff_append₂₆)
+(sole₁₅)-value head-(cons₁₆)
+(sole₁₇)-value head-(cons₁₈)
+(cons₁₆)-value tail-(cons₁₈)
+(cons₁₈)-value left-(diff₁₉)
+(sole₂₁)-value head-(cons₂₂)
+(sole₂₃)-value head-(cons₂₄)
+(cons₂₂)-value tail-(cons₂₄)
+(cons₂₄)-value left-(diff₂₅)
+(diff₁₉)-value right-(diff_append₂₆)
 (diff₁₉)-right tail-(cons₁₆)
 (diff₂₅)-right tail-(cons₂₂)
 (diff_append₂₆)-return
\ No newline at end of file
diff --git a/docs/tests/List.inet b/docs/tests/List.inet
index 4d0b7b04..00be7ffa 100644
--- a/docs/tests/List.inet
+++ b/docs/tests/List.inet
@@ -1,34 +1,34 @@
 defnode sole
   ------
-  return!
+  value!
 end
 
 defnode null
   ------
-  return!
+  value!
 end
 
 defnode cons
   head
   tail
   -------
-  return!
+  value!
 end
 
 defnode append
-  left!
-  right
+  target!
+  rest
   ------
   return
 end
 
 defrule null append
-  (append)-right return-(append)
+  (append)-rest return-(append)
 end
 
 defrule cons append
   (cons)-tail
-  (append)-right
+  (append)-rest
   append
   (cons)-head cons
   return-(append)
diff --git a/docs/tests/List.inet.six_soles.finial.txt b/docs/tests/List.inet.six_soles.finial.txt
index 094d3842..b6556f7d 100644
--- a/docs/tests/List.inet.six_soles.finial.txt
+++ b/docs/tests/List.inet.six_soles.finial.txt
@@ -1,13 +1,13 @@
-(sole₁₂)-return head-(cons₁₇)
-(sole₅)-return head-(cons₁₉)
-(cons₁₉)-return tail-(cons₁₇)
-(sole₁₀)-return head-(cons₂₁)
-(cons₂₁)-return tail-(cons₁₉)
-(sole₃)-return head-(cons₂₃)
-(cons₂₃)-return tail-(cons₂₁)
-(sole₈)-return head-(cons₂₅)
-(cons₂₅)-return tail-(cons₂₃)
-(sole₁)-return head-(cons₂₇)
-(cons₂₇)-return tail-(cons₂₅)
-(null₀)-return tail-(cons₂₇)
-(cons₁₇)-return
\ No newline at end of file
+(sole₁₂)-value head-(cons₁₇)
+(sole₅)-value head-(cons₁₉)
+(cons₁₉)-value tail-(cons₁₇)
+(sole₁₀)-value head-(cons₂₁)
+(cons₂₁)-value tail-(cons₁₉)
+(sole₃)-value head-(cons₂₃)
+(cons₂₃)-value tail-(cons₂₁)
+(sole₈)-value head-(cons₂₅)
+(cons₂₅)-value tail-(cons₂₃)
+(sole₁)-value head-(cons₂₇)
+(cons₂₇)-value tail-(cons₂₅)
+(null₀)-value tail-(cons₂₇)
+(cons₁₇)-value
\ No newline at end of file
diff --git a/docs/tests/List.inet.six_soles.initial.txt b/docs/tests/List.inet.six_soles.initial.txt
index 9ecee03c..a3762454 100644
--- a/docs/tests/List.inet.six_soles.initial.txt
+++ b/docs/tests/List.inet.six_soles.initial.txt
@@ -1,15 +1,15 @@
-(cons₁₃)-return!left-(append₁₄)
-(sole₁)-return head-(cons₂)
-(null₀)-return tail-(cons₂)
-(sole₃)-return head-(cons₄)
-(cons₂)-return tail-(cons₄)
-(sole₅)-return head-(cons₆)
-(cons₄)-return tail-(cons₆)
-(sole₈)-return head-(cons₉)
-(null₇)-return tail-(cons₉)
-(sole₁₀)-return head-(cons₁₁)
-(cons₉)-return tail-(cons₁₁)
-(sole₁₂)-return head-(cons₁₃)
-(cons₁₁)-return tail-(cons₁₃)
-(cons₆)-return right-(append₁₄)
+(cons₁₃)-value!target-(append₁₄)
+(sole₁)-value head-(cons₂)
+(null₀)-value tail-(cons₂)
+(sole₃)-value head-(cons₄)
+(cons₂)-value tail-(cons₄)
+(sole₅)-value head-(cons₆)
+(cons₄)-value tail-(cons₆)
+(sole₈)-value head-(cons₉)
+(null₇)-value tail-(cons₉)
+(sole₁₀)-value head-(cons₁₁)
+(cons₉)-value tail-(cons₁₁)
+(sole₁₂)-value head-(cons₁₃)
+(cons₁₁)-value tail-(cons₁₃)
+(cons₆)-value rest-(append₁₄)
 (append₁₄)-return
\ No newline at end of file
diff --git a/docs/tests/Nat.inet b/docs/tests/Nat.inet
index 9a3187b5..d47a03ca 100644
--- a/docs/tests/Nat.inet
+++ b/docs/tests/Nat.inet
@@ -1,16 +1,15 @@
-defnode zero -- return! end
+defnode zero -- value! end
 
-defnode add1 prev -- return! end
+defnode add1 prev -- value! end
 
-defnode add x! y -- return end
+defnode add target! addend -- return end
 
 defrule zero add
-  (add)-y return-(add)
+  (add)-addend return-(add)
 end
 
 defrule add1 add
-  (add1)-prev (add)-y
-  add add1
+  (add1)-prev (add)-addend add add1
   return-(add)
 end
 
diff --git a/docs/tests/Nat.inet.four.finial.txt b/docs/tests/Nat.inet.four.finial.txt
index 2a3b0902..c6b9ac00 100644
--- a/docs/tests/Nat.inet.four.finial.txt
+++ b/docs/tests/Nat.inet.four.finial.txt
@@ -1,5 +1,5 @@
-(add1₃₅)-return prev-(add1₂₉)
-(add1₃₇)-return prev-(add1₃₅)
-(add1₄₁)-return prev-(add1₃₇)
-(zero₁₄)-return prev-(add1₄₁)
-(add1₂₉)-return
\ No newline at end of file
+(add1₃₅)-value prev-(add1₂₉)
+(add1₃₇)-value prev-(add1₃₅)
+(add1₄₁)-value prev-(add1₃₇)
+(zero₁₄)-value prev-(add1₄₁)
+(add1₂₉)-value
\ No newline at end of file
diff --git a/docs/tests/Nat.inet.four.initial.txt b/docs/tests/Nat.inet.four.initial.txt
index 86f0d4ef..0f6fdb20 100644
--- a/docs/tests/Nat.inet.four.initial.txt
+++ b/docs/tests/Nat.inet.four.initial.txt
@@ -1,11 +1,11 @@
-(add1₁₇)-return!x-(add₁₈)
-(add1₂₂)-return!x-(add₂₃)
-(zero₁₄)-return prev-(add1₁₅)
-(zero₁₆)-return prev-(add1₁₇)
-(add1₁₅)-return y-(add₁₈)
-(zero₁₉)-return prev-(add1₂₀)
-(zero₂₁)-return prev-(add1₂₂)
-(add1₂₀)-return y-(add₂₃)
-(add₂₃)-return x-(add₂₄)
-(add₁₈)-return y-(add₂₄)
+(add1₁₇)-value!target-(add₁₈)
+(add1₂₂)-value!target-(add₂₃)
+(zero₁₄)-value prev-(add1₁₅)
+(zero₁₆)-value prev-(add1₁₇)
+(add1₁₅)-value addend-(add₁₈)
+(zero₁₉)-value prev-(add1₂₀)
+(zero₂₁)-value prev-(add1₂₂)
+(add1₂₀)-value addend-(add₂₃)
+(add₂₃)-return target-(add₂₄)
+(add₁₈)-return addend-(add₂₄)
 (add₂₄)-return
\ No newline at end of file
diff --git a/docs/tests/Nat.inet.two.finial.txt b/docs/tests/Nat.inet.two.finial.txt
index fdea242d..a8fbd2bb 100644
--- a/docs/tests/Nat.inet.two.finial.txt
+++ b/docs/tests/Nat.inet.two.finial.txt
@@ -1,3 +1,3 @@
-(add1₁₃)-return prev-(add1₁₁)
-(zero₄)-return prev-(add1₁₃)
-(add1₁₁)-return
\ No newline at end of file
+(add1₁₃)-value prev-(add1₁₁)
+(zero₄)-value prev-(add1₁₃)
+(add1₁₁)-value
\ No newline at end of file
diff --git a/docs/tests/Nat.inet.two.initial.txt b/docs/tests/Nat.inet.two.initial.txt
index a4afe7e1..d7a22242 100644
--- a/docs/tests/Nat.inet.two.initial.txt
+++ b/docs/tests/Nat.inet.two.initial.txt
@@ -1,5 +1,5 @@
-(add1₇)-return!x-(add₈)
-(zero₄)-return prev-(add1₅)
-(zero₆)-return prev-(add1₇)
-(add1₅)-return y-(add₈)
+(add1₇)-value!target-(add₈)
+(zero₄)-value prev-(add1₅)
+(zero₆)-value prev-(add1₇)
+(add1₅)-value addend-(add₈)
 (add₈)-return
\ No newline at end of file
diff --git a/docs/tests/Nat.inet.zero_zero_add.finial.txt b/docs/tests/Nat.inet.zero_zero_add.finial.txt
index fb8d110a..80c59296 100644
--- a/docs/tests/Nat.inet.zero_zero_add.finial.txt
+++ b/docs/tests/Nat.inet.zero_zero_add.finial.txt
@@ -1 +1 @@
-(zero₀)-return
\ No newline at end of file
+(zero₀)-value
\ No newline at end of file
diff --git a/docs/tests/Nat.inet.zero_zero_add.initial.txt b/docs/tests/Nat.inet.zero_zero_add.initial.txt
index de846e2d..dbfe9818 100644
--- a/docs/tests/Nat.inet.zero_zero_add.initial.txt
+++ b/docs/tests/Nat.inet.zero_zero_add.initial.txt
@@ -1,3 +1,3 @@
-(zero₁)-return!x-(add₂)
-(zero₀)-return y-(add₂)
+(zero₁)-value!target-(add₂)
+(zero₀)-value addend-(add₂)
 (add₂)-return
\ No newline at end of file