diff --git a/README.md b/README.md
index bc277a0..9c96e16 100644
--- a/README.md
+++ b/README.md
@@ -234,8 +234,11 @@ Root Action                             o---|---x
 - the base/root action can return any value.  
   **Notes:**  
     - if undefined is returned, it will be replaced by the 
-		  action context/action set.
-	- `false` and `null` are returned as-is.
+		  action context/action set,
+	- if a function is returned it is treated as a post phase action,
+	- to return a reserved value (undefined, function) wrap it in 
+		  `actions.ASIS(..)`
+	- any other return value is returned as-is,
     - there is no distinction between root and other actions
 		  other than that root action's return values are not 
 		  ignored.
diff --git a/actions.js b/actions.js
index afd517f..305517f 100755
--- a/actions.js
+++ b/actions.js
@@ -15,8 +15,14 @@ var object = require('ig-object')
 
 var args2array = function(a){ return [].slice.call(a) } 
 
+var ASIS =
+module.ASIS = 
+object.makeConstructor('ASIS', {
+	__init__: function(obj){ this.value = obj },
+})
+
 var UNDEFINED =
-module.UNDEFINED = ['undefined placeholder']
+module.UNDEFINED = ASIS(undefined)
 
 
 
@@ -792,7 +798,7 @@ Action.prototype.pre = function(context, args){
 
 	// return context if nothing specific is returned...
 	res = res === undefined ? context 
-		: res === UNDEFINED ? undefined 
+		: res instanceof ASIS ? res.value
 		// XXX returning an explicit [undefined]...
 		//: res instanceof Array
 		//		&& res.length == 1
diff --git a/package.json b/package.json
index 3a26c67..ccda09e 100755
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "ig-actions",
-  "version": "3.20.2",
+  "version": "3.21.0",
   "description": "",
   "main": "actions.js",
   "scripts": {