diff --git a/operational b/operational
index 83d238ac74a346daec58f9b9a2b2581920bfbe00..756b36d50924e433c506b26cef562d5d528a576c 100644
--- a/operational
+++ b/operational
@@ -37,6 +37,14 @@ Time-stamp: <2017-01-27>
     not modify the number.
 
 * later                                                               :entry:
+** 2017-01-27 the whole FSM can be made persistent across sessions.
+not only trail.
+
+- load FSM data on page init.
+- save FSM data on each call to FSM functions.
+
+The usefulness is doubtful. I will leave it.
+
 ** 2017-01-26 make the whole thing a polymer web component
 <rpn-calculator trail="true"></rpn-calculator>
 
@@ -48,13 +56,26 @@ the parent DOM.
 
 * current                                                             :entry:
 ** 
-** 2017-01-27 feature: long press backspace just delete the current number.
+** 2017-01-27 add some visual feedback when clicking a button. like in material design.
 ** 2017-01-27 UI problem: when input a very large number, #number-display and keyboard will grow.
 should set a max-width on #number-display.
 
 overflow: auto
 doesn't work with <td> in firefox.
 
+** 2017-01-26 make it work offline, add sw.js
+** 2017-01-26 make undo work
+* done                                                                :entry:
+** 2017-01-26 make basic things work.
+- DONE draw the keyboard using HTML and CSS
+- DONE make basic number input and arithmetic work
+- DONE make DUP and SWP work
+- DONE make trail work
+** 2017-01-26 make trail persistent
+trail is a bounded fifo queue, it just store recent 1k entries.
+when multiple instances of calculator is working. they all write to a single
+trail cache. it's not a problem.
+
 ** 2017-01-27 make trail work
 - when is trail being updated?
   - when a number is committed to number stack. return.
@@ -91,19 +112,6 @@ doesn't work with <td> in firefox.
     it's because shortKeyNames key should be key name string literal, not the
     js constant identifier.
 
-** 2017-01-26 make trail persistent
-trail is a bounded fifo queue, it just store recent 1k entries.
-when multiple instances of calculator is working. they all write to a single
-trail cache. it's not a problem.
-
-** 2017-01-26 make it work offline, add sw.js
-** 2017-01-26 make undo work
-** 2017-01-26 make basic things work.
-- DONE draw the keyboard using HTML and CSS
-- DONE make basic number input and arithmetic work
-- DONE make DUP and SWP work
-- make trail work
-* done                                                                :entry:
 ** 2017-01-27 design a layout for mobile.
 - layout on mobile:
   stack
@@ -186,7 +194,7 @@ update isNumberKey().
 
 ** 2017-01-26 make basic number input and arithmetic work
 - DONE make event work.
-  - TODO add some visual feedback when clicking a button. like in material design.
+  - MOVED add some visual feedback when clicking a button. like in material design.
 - DONE design data structure for the calculator.
 - DONE add unit test for the data structure and functions.
 - DONE make number input and simple calculation work.
@@ -216,3 +224,6 @@ add this button. move divide button to somewhere else.
 
 ** 2017-01-26 draw the keyboard using HTML and CSS
 * wontfix                                                             :entry:
+** 2017-01-27 feature: long press backspace just delete the current number.
+there is no long press mouse event.
+won't add this feature.