diff --git a/README.md b/README.md
index 02b5c40..04ff6b3 100644
--- a/README.md
+++ b/README.md
@@ -37,6 +37,7 @@ This code is an evolution of that parser.
   - Hooks for dynamic option/command handling
   - Customizable error and stop condition handling
 
+
 ## Planned Features
 
 - Run `<command>-<sub-command>` scripts
@@ -84,7 +85,7 @@ This code is an evolution of that parser.
 				- [More control over help...](#more-control-over-help)
 		- [Nested parsers](#nested-parsers)
 	- [Components and API](#components-and-api)
-		- [`THEN`, `STOP` and `ERROR`](#then-stop-and-error)
+		- [`THEN`/ `STOP`](#then-stop)
 		- [`ParserError(..)`](#parsererror)
 		- [`Parser(..)`](#parser)
 			- [`<parser>.then(..)`](#parserthen)
@@ -231,10 +232,12 @@ $ ./script.js -fb
 
 ```
 
+
 ## Error reporting
 
 XXX
 
+
 ## XXX add subsections by task
 
 XXX
@@ -242,6 +245,7 @@ XXX
 XXX might be a good idea to split out the rest to a INDETAIL.md or similar...
 
 
+
 ## Configuration
 
 ```
@@ -332,9 +336,9 @@ A _value_ can be passed either explicitly passed (via `=` syntax),
 implicitly parsed from the `argv` via the `<option>.arg` definition or 
 is `undefined` otherwise.
 
-A handler can return one of the `THEN`, `STOP` or `ERROR` to control
-further parsing and/or execution.
-(See: [`THEN`, `STOP` and `ERROR`](#then-stop-and-error) for more info.)
+A handler can return one of the `THEN`, `STOP` or `ParserError` instance 
+to control further parsing and/or execution.
+(See: [`THEN` / `STOP`](#then-stop) for more info.)
 
 
 #### `<option>.doc`
@@ -468,6 +472,7 @@ argv.Parser.valueCollectors.Set = function(value, current, key){
 Defining handlers local to a parser instance handler is the same as for 
 [type handlers](#optiontype) above.
 
+
 #### `<option>.env`
 
 Determines the environment variable to be used as the default value for
@@ -691,26 +696,29 @@ See [lang.js](./lang.js) for more fun with argv and programming languages ;)
 
 ## Components and API
 
-### `THEN`, `STOP` and `ERROR`
+### `THEN` / `STOP`
 
 Values that if returned by option/command handlers can control the parse flow.
 
 - `THEN` &ndash; Stop parsing and call `<parser>.then(..)` callbacks.
 - `STOP` &ndash; Stop parsing and call `<parser>.stop(..)` callbacks, 
   skipping `<parser>.then(..)`.
-- `ERROR` &ndash; Stop parsing, call `<parser>.error(..)` callbacks and
-  exit with an error.
+
 
 ### `ParserError(..)` 
 
-A base error constructor, if an instance of `ParseError` is thrown by the 
-handler it has the same effect as returning `ERROR` with one difference being
-that the error `.name`/`.message` will get printed.
+A base error constructor. 
+
+If an instance of `ParseError` is thrown or returned by the handler parsing
+is stopped, `<parsing>.error(..)` is called and then the parser will exit 
+with an error (see: [`<parser>.handleErrorExit(..)`](#parserhandleerrorexit)).
 
 The following error constructors are also defined:
 - `ParserTypeError(..)`
 - `ParserValueError(..)`
 
+Note that `ParserError` instances can be both returned or thrown.
+
 
 ### `Parser(..)` 
 
@@ -722,6 +730,7 @@ Parser(<spec>)
 
 See [`<parser>(..)`](#parser-1) for more info.
 
+
 #### `<parser>.then(..)`
 
 Add callback to `then` "event".
@@ -738,6 +747,7 @@ callback(<unhandled>, <root-value>, <rest>)
 `then` is triggered when parsing is done or stopped from an option
 handler by returning `THEN`.
 
+
 #### `<parser>.stop(..)`
 
 Add callback to `stop` "event".
@@ -753,6 +763,7 @@ callback(<arg>, <rest>)
 
 `stop` is triggered when a handler returns `STOP`.
 
+
 #### `<parser>.error(..)`
 
 Add callback to `error` "event".
@@ -777,6 +788,7 @@ Remove callback from "event".
 		-> <parser>
 ```
 
+
 #### `<parser>(..)`
 
 Execute the `parser` instance.
diff --git a/argv.js b/argv.js
index 983125f..0bfc7f1 100644
--- a/argv.js
+++ b/argv.js
@@ -33,9 +33,8 @@ module.STOP =
 module.THEN = 
 	{doc: 'break option processing, triggers .then(..) handlers'}
 
-module.ERROR = 
-	{doc: 'option processing error, triggers .error(..) handlers'}
 
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
 
 module.ParserError = 
 	object.Constructor('ParserError', Error, {
@@ -664,8 +663,9 @@ object.Constructor('Parser', {
 		doc: false,
 		//section_doc: ...,
 		handler: function(_, key){
-			this.printError('unknown '+ (key.startsWith('-') ? 'option:' : 'command:'), key)
-			return module.ERROR } },
+			return this.printError(
+				module.ParserError(
+					`Unknown ${key.startsWith('-') ? 'option:' : 'command:'} ${ key }`)) } },
 	'@*': '-*',
 	
 
@@ -676,7 +676,18 @@ object.Constructor('Parser', {
 	print: afterCallback('print', null, function(...args){
 		console.log(...args)
 		return this }),
+	//
+	// 	.printError(...)
+	// 		-> this
+	//
+	// 	.printError(error, ...)
+	// 		-> error
+	//
 	printError: afterCallback('print_error', null, function(...args){
+		if(args[0] instanceof module.ParserError){
+			console.error(
+				this.scriptName+':', args[0].name+':', args[0].message, ...args.slice(1))
+			return args[0] }
 		console.error(this.scriptName+': Error:', ...args)
 		return this }),
 
@@ -838,6 +849,12 @@ object.Constructor('Parser', {
 			parsed.error(reason, arg, rest)
 			parsed.handleErrorExit
 				&& parsed.handleErrorExit(arg, reason) }
+		var reportError = function(message, arg, rest){
+			message = message
+				.replace(/$ARG/g, arg)
+			handleError(message, arg, rest)
+			return parsed.printError(
+				module.ParserError(message)) }
 		var runHandler = function(handler, arg, rest){
 			var [arg, value] = arg instanceof Array ?
 				arg
@@ -858,9 +875,7 @@ object.Constructor('Parser', {
 				: value
 			// required value check...
 			if(handler.valueRequired && value == null){
-				handleError('value missing', arg, rest)
-				parsed.printError('value missing:', arg+'=?')
-				return module.ERROR }
+				return reportError('Value missing: $ARG=?', arg, rest) }
 
 			try {
 				// run handler...
@@ -880,8 +895,6 @@ object.Constructor('Parser', {
 				&& parsed.stop(arg, rest)
 			res instanceof module.ParserError
 				&& handleError(res, arg, rest)
-			res === module.ERROR
-				&& handleError('unknown', arg, rest)
 			return res }
 		// NOTE: if successful this needs to modify the arg, thus it 
 		// 		returns both the new first arg and the handler...
@@ -900,8 +913,7 @@ object.Constructor('Parser', {
 				&& r.push(r.pop() +'='+ value) 
 			// push new options back to option "stack"...
 			rest.splice(0, 0, ...r)
-			var handler = parsed.handler(a)[1]
-			return [a, handler] }
+			return [ a, parsed.handler(a)[1] ] }
 
 		// parse/interpret the arguments and call handlers...
 		var values = new Set()
@@ -936,9 +948,7 @@ object.Constructor('Parser', {
 					|| parsed.handler(dfl)[1]
 				// no handler found and '-*' or '@*' not defined...
 				if(handler == null){
-					handleError('unknown', arg, rest)
-					parsed.printError('unknown '+(type == 'opt' ? 'option:' : 'command:'), arg)
-					return module.ERROR }
+					return reportError(`Unknown ${ type == 'opt' ? 'option' : 'command:' } $ARG`, arg, rest) }
 
 				// mark handler...
 				;(handler.env || 'default' in handler)
@@ -949,7 +959,6 @@ object.Constructor('Parser', {
 
 				// handle stop conditions...
 				if(res === module.STOP 
-						|| res === module.ERROR 
 						|| res instanceof module.ParserError){
 					return nested ?
 						res
@@ -981,8 +990,7 @@ object.Constructor('Parser', {
 				.map(function([k, a, d, h]){
 					return k.pop() })
 		if(missing.length > 0){
-			handleError('required', missing, rest)
-			parsed.printError('required but missing:', missing.join(', '))
+			reportError('required but missing: $ARG', missing.join(', '), rest)
 			return parsed }
 
 		// handle root value...
diff --git a/package.json b/package.json
index 440c3a4..61f5599 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "ig-argv",
-  "version": "2.5.0",
+  "version": "2.6.0",
   "description": "simple argv parser",
   "main": "argv.js",
   "scripts": {
diff --git a/test.js b/test.js
index d810847..eeee14b 100644
--- a/test.js
+++ b/test.js
@@ -75,7 +75,7 @@ argv.Parser({
 		},
 		'-s': '-string',
 		'-string': {
-			doc: 'collect STR',
+			doc: 'collect tab-separated strings',
 			arg: 'STR | str',
 			collect: 'string|\t',
 		},
@@ -84,13 +84,13 @@ argv.Parser({
 			doc: 'short option', },
 
 		'-type-error': {
-			doc: 'throw an type error',
+			doc: 'throw a type error',
 			type: 'error', 
 		},
 		'-error': {
 			doc: 'throw an error',
 			handler: function(){
-				throw argv.ParserError('error') }},
+				return argv.ParserError('error') }},
 
 
 		'-test': argv.Parser({