diff --git a/TinyFrame.c b/TinyFrame.c
index b8af068..dac526b 100644
--- a/TinyFrame.c
+++ b/TinyFrame.c
@@ -23,7 +23,7 @@ enum TFState {
 
 typedef struct _IdListener_struct_ {
 	TF_ID id;
-	TF_LISTENER fn;
+	TF_Listener fn;
 	TF_TICKS timeout;     // nr of ticks remaining to disable this listener
 	TF_TICKS timeout_max; // the original timeout is stored here
 	void *userdata;
@@ -31,11 +31,11 @@ typedef struct _IdListener_struct_ {
 
 typedef struct _TypeListener_struct_ {
 	TF_TYPE type;
-	TF_LISTENER fn;
+	TF_Listener fn;
 } TypeListener;
 
 typedef struct _GenericListener_struct_ {
-	TF_LISTENER fn;
+	TF_Listener fn;
 } GenericListener;
 
 /**
@@ -43,7 +43,7 @@ typedef struct _GenericListener_struct_ {
  */
 static struct TinyFrameStruct {
 	/* Own state */
-	TF_PEER peer_bit;       //!< Own peer bit (unqiue to avoid msg ID clash)
+	TF_Peer peer_bit;       //!< Own peer bit (unqiue to avoid msg ID clash)
 	TF_ID next_id;          //!< Next frame / frame chain ID
 
 	/* Parser state */
@@ -201,7 +201,7 @@ static struct TinyFrameStruct {
 //endregion
 
 
-void _TF_FN TF_Init(TF_PEER peer_bit)
+void _TF_FN TF_Init(TF_Peer peer_bit)
 {
 	// Zero it out
 	memset(&tf, 0, sizeof(struct TinyFrameStruct));
@@ -211,6 +211,11 @@ void _TF_FN TF_Init(TF_PEER peer_bit)
 
 //region Listeners
 
+static void _TF_FN renew_id_listener(IdListener *lst)
+{
+	lst->timeout = lst->timeout_max;
+}
+
 /**
  * Notify callback about ID listener demise & clean it
  *
@@ -218,12 +223,16 @@ void _TF_FN TF_Init(TF_PEER peer_bit)
  */
 static void _TF_FN cleanup_id_listener(TF_COUNT i, IdListener *lst)
 {
-	TF_MSG msg;
+	TF_Msg msg;
 	if (lst->fn == NULL) return;
 
-	msg.userdata = lst->userdata;
-	msg.data = NULL; // this is a signal that the listener should clean up
-	lst->fn(&msg);
+	// Make user clean up their data - only if not NULL
+	if (lst->userdata != NULL) {
+		msg.userdata = lst->userdata;
+		msg.data = NULL; // this is a signal that the listener should clean up
+		lst->fn(&msg); // return value is ignored here - use TF_STAY or TF_CLOSE
+	}
+
 	lst->fn = NULL; // Discard listener
 
 	if (i == tf.count_id_lst - 1) {
@@ -257,7 +266,7 @@ static inline void _TF_FN cleanup_generic_listener(TF_COUNT i, GenericListener *
 	}
 }
 
-bool _TF_FN TF_AddIdListener(TF_MSG *msg, TF_LISTENER cb, TF_TICKS timeout)
+bool _TF_FN TF_AddIdListener(TF_Msg *msg, TF_Listener cb, TF_TICKS timeout)
 {
 	TF_COUNT i;
 	IdListener *lst;
@@ -278,7 +287,7 @@ bool _TF_FN TF_AddIdListener(TF_MSG *msg, TF_LISTENER cb, TF_TICKS timeout)
 	return false;
 }
 
-bool _TF_FN TF_AddTypeListener(TF_TYPE frame_type, TF_LISTENER cb)
+bool _TF_FN TF_AddTypeListener(TF_TYPE frame_type, TF_Listener cb)
 {
 	TF_COUNT i;
 	TypeListener *lst;
@@ -297,7 +306,7 @@ bool _TF_FN TF_AddTypeListener(TF_TYPE frame_type, TF_LISTENER cb)
 	return false;
 }
 
-bool _TF_FN TF_AddGenericListener(TF_LISTENER cb)
+bool _TF_FN TF_AddGenericListener(TF_Listener cb)
 {
 	TF_COUNT i;
 	GenericListener *lst;
@@ -345,7 +354,7 @@ bool _TF_FN TF_RemoveTypeListener(TF_TYPE type)
 	return false;
 }
 
-bool _TF_FN TF_RemoveGenericListener(TF_LISTENER cb)
+bool _TF_FN TF_RemoveGenericListener(TF_Listener cb)
 {
 	TF_COUNT i;
 	GenericListener *lst;
@@ -367,9 +376,10 @@ static void _TF_FN TF_HandleReceivedMessage(void)
 	IdListener *ilst;
 	TypeListener *tlst;
 	GenericListener *glst;
+	TF_Result res;
 
 	// Prepare message object
-	TF_MSG msg;
+	TF_Msg msg;
 	msg.frame_id = tf.id;
 	msg.is_response = false;
 	msg.type = tf.type;
@@ -388,10 +398,19 @@ static void _TF_FN TF_HandleReceivedMessage(void)
 	for (i = 0; i < tf.count_id_lst; i++) {
 		ilst = &tf.id_listeners[i];
 		if (ilst->fn && ilst->id == msg.frame_id) {
-			msg.renew = false;
 			msg.userdata = ilst->userdata; // pass userdata pointer to the callback
-			if (ilst->fn(&msg)) return;
+			res = ilst->fn(&msg);
 			ilst->userdata = msg.userdata; // put it back (may have changed the pointer or set to NULL)
+
+			if (res != TF_NEXT) {
+				if (res == TF_CLOSE) {
+					cleanup_id_listener(i, ilst);
+				}
+				else if (res == TF_RENEW) {
+					renew_id_listener(ilst);
+				}
+				return;
+			}
 		}
 	}
 	msg.userdata = NULL;
@@ -401,7 +420,14 @@ static void _TF_FN TF_HandleReceivedMessage(void)
 	for (i = 0; i < tf.count_type_lst; i++) {
 		tlst = &tf.type_listeners[i];
 		if (tlst->fn && tlst->type == msg.type) {
-			if (tlst->fn(&msg)) return;
+			res = tlst->fn(&msg);
+
+			if (res != TF_NEXT) {
+				if (res == TF_CLOSE) {
+					cleanup_type_listener(i, tlst);
+				}
+				return;
+			}
 		}
 	}
 
@@ -409,7 +435,14 @@ static void _TF_FN TF_HandleReceivedMessage(void)
 	for (i = 0; i < tf.count_generic_lst; i++) {
 		glst = &tf.generic_listeners[i];
 		if (glst->fn) {
-			if (glst->fn(&msg)) return;
+			res = glst->fn(&msg);
+
+			if (res != TF_NEXT) {
+				if (res == TF_CLOSE) {
+					cleanup_generic_listener(i, glst);
+				}
+				return;
+			}
 		}
 	}
 }
@@ -671,7 +704,7 @@ static inline size_t _TF_FN TF_Compose(uint8_t *outbuff, TF_ID *id_ptr,
 }
 
 // send without listener
-bool _TF_FN TF_Send(TF_MSG *msg)
+bool _TF_FN TF_Send(TF_Msg *msg)
 {
 	return TF_Query(msg, NULL, 0);
 }
@@ -679,7 +712,7 @@ bool _TF_FN TF_Send(TF_MSG *msg)
 // send without listener and struct
 bool _TF_FN TF_SendSimple(TF_TYPE type, const uint8_t *data, TF_LEN len)
 {
-	TF_MSG msg;
+	TF_Msg msg;
 	TF_ClearMsg(&msg);
 	msg.type = type;
 	msg.data = data;
@@ -688,9 +721,9 @@ bool _TF_FN TF_SendSimple(TF_TYPE type, const uint8_t *data, TF_LEN len)
 }
 
 // send without listener and struct
-bool _TF_FN TF_QuerySimple(TF_TYPE type, const uint8_t *data, TF_LEN len, TF_LISTENER listener, TF_TICKS timeout)
+bool _TF_FN TF_QuerySimple(TF_TYPE type, const uint8_t *data, TF_LEN len, TF_Listener listener, TF_TICKS timeout)
 {
-	TF_MSG msg;
+	TF_Msg msg;
 	TF_ClearMsg(&msg);
 	msg.type = type;
 	msg.data = data;
@@ -699,7 +732,7 @@ bool _TF_FN TF_QuerySimple(TF_TYPE type, const uint8_t *data, TF_LEN len, TF_LIS
 }
 
 // send with listener
-bool _TF_FN TF_Query(TF_MSG *msg, TF_LISTENER listener, TF_TICKS timeout)
+bool _TF_FN TF_Query(TF_Msg *msg, TF_Listener listener, TF_TICKS timeout)
 {
 	size_t len;
 	len = TF_Compose(tf.sendbuf,
@@ -719,13 +752,10 @@ bool _TF_FN TF_Query(TF_MSG *msg, TF_LISTENER listener, TF_TICKS timeout)
 }
 
 // Like TF_Send, but with explicit frame ID
-bool _TF_FN TF_Respond(TF_MSG *msg)
+bool _TF_FN TF_Respond(TF_Msg *msg)
 {
 	msg->is_response = true;
-	bool suc = TF_Send(msg);
-
-	if (suc && msg->renew) TF_RenewIdListener(msg->frame_id);
-	return suc;
+	return TF_Send(msg);
 }
 
 bool _TF_FN TF_RenewIdListener(TF_ID id)
@@ -736,7 +766,7 @@ bool _TF_FN TF_RenewIdListener(TF_ID id)
 		lst = &tf.id_listeners[i];
 		// test if live & matching
 		if (lst->fn != NULL && lst->id == id) {
-			lst->timeout = lst->timeout_max;
+			renew_id_listener(lst);
 			return true;
 		}
 	}
diff --git a/TinyFrame.h b/TinyFrame.h
index 1ada271..c724a24 100644
--- a/TinyFrame.h
+++ b/TinyFrame.h
@@ -87,8 +87,15 @@
 /** Peer bit enum (used for init) */
 typedef enum {
 	TF_SLAVE = 0,
-	TF_MASTER = 1
-} TF_PEER;
+	TF_MASTER,
+} TF_Peer;
+
+typedef enum {
+	TF_NEXT = 0,   //!< Not handled, let other listeners handle it
+	TF_STAY = 1,   //!< Handled, stay
+	TF_RENEW = 2,  //!< Handled, stay, renew - useful only with listener timeout
+	TF_CLOSE = 3,  //!< Handled, remove self
+} TF_Result;
 
 /** Data structure for sending / receiving messages */
 typedef struct _TF_MSG_STRUCT_ {
@@ -98,13 +105,12 @@ typedef struct _TF_MSG_STRUCT_ {
 	const uint8_t *data;  //!< buffer of received data or data to send. NULL = listener timed out, free userdata!
 	TF_LEN len;           //!< length of the buffer
 	void *userdata;       //!< here's a place for custom data; this data will be stored with the listener
-	bool renew;           //!< Renew the ID listener - if using timeout
-} TF_MSG;
+} TF_Msg;
 
 /**
  * Clear message struct
  */
-static inline void TF_ClearMsg(TF_MSG *msg)
+static inline void TF_ClearMsg(TF_Msg *msg)
 {
 	msg->frame_id = 0;
 	msg->is_response = false;
@@ -112,7 +118,6 @@ static inline void TF_ClearMsg(TF_MSG *msg)
 	msg->data = NULL;
 	msg->len = 0;
 	msg->userdata = NULL;
-	msg->renew = false;
 }
 
 /**
@@ -122,9 +127,9 @@ static inline void TF_ClearMsg(TF_MSG *msg)
  * @param type - type field from the message
  * @param data - byte buffer with the application data
  * @param len - number of bytes in the buffer
- * @return true if the frame was consumed
+ * @return listener result
  */
-typedef bool (*TF_LISTENER)(TF_MSG *msg);
+typedef TF_Result (*TF_Listener)(TF_Msg *msg);
 
 /**
  * Initialize the TinyFrame engine.
@@ -132,7 +137,7 @@ typedef bool (*TF_LISTENER)(TF_MSG *msg);
  *
  * @param peer_bit - peer bit to use for self
  */
-void TF_Init(TF_PEER peer_bit);
+void TF_Init(TF_Peer peer_bit);
 
 /**
  * Reset the frame parser state machine.
@@ -148,7 +153,7 @@ void TF_ResetParser(void);
  * @param timeout - timeout in ticks to auto-remove the listener (0 = keep forever)
  * @return slot index (for removing), or TF_ERROR (-1)
  */
-bool TF_AddIdListener(TF_MSG *msg, TF_LISTENER cb, TF_TICKS timeout);
+bool TF_AddIdListener(TF_Msg *msg, TF_Listener cb, TF_TICKS timeout);
 
 /**
  * Remove a listener by the message ID it's registered for
@@ -164,7 +169,7 @@ bool TF_RemoveIdListener(TF_ID frame_id);
  * @param cb - callback
  * @return slot index (for removing), or TF_ERROR (-1)
  */
-bool TF_AddTypeListener(TF_TYPE frame_type, TF_LISTENER cb);
+bool TF_AddTypeListener(TF_TYPE frame_type, TF_Listener cb);
 
 /**
  * Remove a listener by type.
@@ -179,14 +184,14 @@ bool TF_RemoveTypeListener(TF_TYPE type);
  * @param cb - callback
  * @return slot index (for removing), or TF_ERROR (-1)
  */
-bool TF_AddGenericListener(TF_LISTENER cb);
+bool TF_AddGenericListener(TF_Listener cb);
 
 /**
  * Remove a generic listener by function pointer
  *
  * @param cb - callback function to remove
  */
-bool TF_RemoveGenericListener(TF_LISTENER cb);
+bool TF_RemoveGenericListener(TF_Listener cb);
 
 /**
  * Send a frame, no listener
@@ -194,7 +199,7 @@ bool TF_RemoveGenericListener(TF_LISTENER cb);
  * @param msg - message struct. ID is stored in the frame_id field
  * @return success
  */
-bool TF_Send(TF_MSG *msg);
+bool TF_Send(TF_Msg *msg);
 
 /**
  * Like TF_Send, but without the struct
@@ -204,7 +209,7 @@ bool TF_SendSimple(TF_TYPE type, const uint8_t *data, TF_LEN len);
 /**
  * Like TF_Query, but without the struct
  */
-bool TF_QuerySimple(TF_TYPE type, const uint8_t *data, TF_LEN len, TF_LISTENER listener, TF_TICKS timeout);
+bool TF_QuerySimple(TF_TYPE type, const uint8_t *data, TF_LEN len, TF_Listener listener, TF_TICKS timeout);
 
 /**
  * Send a frame, and optionally attach an ID listener.
@@ -214,7 +219,7 @@ bool TF_QuerySimple(TF_TYPE type, const uint8_t *data, TF_LEN len, TF_LISTENER l
  * @param timeout - listener expiry time in ticks
  * @return success
  */
-bool TF_Query(TF_MSG *msg, TF_LISTENER listener, TF_TICKS timeout);
+bool TF_Query(TF_Msg *msg, TF_Listener listener, TF_TICKS timeout);
 
 /**
  * Send a response to a received message.
@@ -222,7 +227,7 @@ bool TF_Query(TF_MSG *msg, TF_LISTENER listener, TF_TICKS timeout);
  * @param msg - message struct. ID is read from frame_id. set ->renew to reset listener timeout
  * @return success
  */
-bool TF_Respond(TF_MSG *msg);
+bool TF_Respond(TF_Msg *msg);
 
 /**
  * Renew ID listener timeout
diff --git a/demo/demo.c b/demo/demo.c
index 503e382..4b234ff 100644
--- a/demo/demo.c
+++ b/demo/demo.c
@@ -2,10 +2,9 @@
 // Created by MightyPork on 2017/10/15.
 //
 
-// http://www.thegeekstuff.com/2011/12/c-socket-programming/?utm_source=feedburner
-
 #include "demo.h"
 
+// those magic defines are needed so we can use clone()
 #define _GNU_SOURCE
 #define __USE_GNU
 #include <sched.h>
@@ -20,15 +19,24 @@
 volatile int sockfd = -1;
 volatile bool conn_disband = false;
 
+/**
+ * Close socket
+ */
 void demo_disconn(void)
 {
 	conn_disband = true;
 	if (sockfd >= 0) close(sockfd);
 }
 
+/**
+ * Demo WriteImpl - send stuff to our peer
+ *
+ * @param buff
+ * @param len
+ */
 void TF_WriteImpl(const uint8_t *buff, size_t len)
 {
-	printf("\033[32m--- TX %ld bytes ---\033[0m\n", len);
+	printf("\033[32mTF_WriteImpl - sending frame:\033[0m\n");
 	dumpFrame(buff, len);
 	usleep(1000);
 
@@ -39,6 +47,13 @@ void TF_WriteImpl(const uint8_t *buff, size_t len)
 	}
 }
 
+
+/**
+ * Client bg thread
+ *
+ * @param unused
+ * @return unused
+ */
 static int demo_client(void* unused)
 {
 	(void)unused;
@@ -81,6 +96,12 @@ static int demo_client(void* unused)
 	return 0;
 }
 
+/**
+ * Server bg thread
+ *
+ * @param unused
+ * @return unused
+ */
 static int demo_server(void* unused)
 {
 	(void)unused;
@@ -136,20 +157,36 @@ static int demo_server(void* unused)
 	return 0;
 }
 
-void signal_handler(int sig)
+/**
+ * Trap - clean up
+ *
+ * @param sig - signal that caused this
+ */
+static void signal_handler(int sig)
 {
 	(void)sig;
 	printf("Shutting down...");
 	demo_disconn();
-	exit(sig);
+
+	exit(sig); // pass the signal through - this is nonstandard behavior but useful for debugging
 }
 
+/**
+ * Sleaping Beauty's fave function
+ */
 void demo_sleep(void)
 {
 	while(1) usleep(10);
 }
 
-void demo_init(TF_PEER peer)
+/**
+ * Start the background thread
+ *
+ * Slave is started first and doesn't normally init transactions - but it could
+ *
+ * @param peer what peer we are
+ */
+void demo_init(TF_Peer peer)
 {
 	signal(SIGTERM, signal_handler);
 	signal(SIGINT, signal_handler);
@@ -163,6 +200,9 @@ void demo_init(TF_PEER peer)
 	}
 
 	printf("Starting %s...\n", peer == TF_MASTER ? "MASTER" : "SLAVE");
+
+	// CLONE_VM    --- share heap
+	// CLONE_FILES --- share stdout and stderr
 	if (peer == TF_MASTER) {
 		retc = clone(&demo_client, (char *)stack+8192, CLONE_VM|CLONE_FILES, 0);
 	} else {
diff --git a/demo/demo.h b/demo/demo.h
index d5292f4..4caa068 100644
--- a/demo/demo.h
+++ b/demo/demo.h
@@ -15,9 +15,9 @@
 void demo_sleep(void);
 
 /** Init server - DOES NOT init TinyFrame! */
-void demo_init(TF_PEER peer);
+void demo_init(TF_Peer peer);
 
-/** Disconnect client from the server - claled by a server-side callback */
+/** Disconnect client from the server - can be called by a server-side callback */
 void demo_disconn(void);
 
 #endif //TF_DEMO_H
diff --git a/demo/hello/master.c b/demo/hello/master.c
index 5bffbf6..22e5d58 100644
--- a/demo/hello/master.c
+++ b/demo/hello/master.c
@@ -5,18 +5,18 @@
 #include <stdio.h>
 #include "../demo.h"
 
-bool testIdListener(TF_MSG *msg)
+TF_Result testIdListener(TF_Msg *msg)
 {
 	printf("testIdListener()\n");
 	dumpFrameInfo(msg);
-	return true;
+	return TF_CLOSE;
 }
 
-bool testGenericListener(TF_MSG *msg)
+TF_Result testGenericListener(TF_Msg *msg)
 {
 	printf("testGenericListener()\n");
 	dumpFrameInfo(msg);
-	return true;
+	return TF_STAY;
 }
 
 int main(void)
diff --git a/demo/hello/slave.c b/demo/hello/slave.c
index 200b3e2..3493bd1 100644
--- a/demo/hello/slave.c
+++ b/demo/hello/slave.c
@@ -6,14 +6,14 @@
 #include "../demo.h"
 #include <memory.h>
 
-bool helloListener(TF_MSG *msg)
+TF_Result helloListener(TF_Msg *msg)
 {
 	printf("helloListener()\n");
 	dumpFrameInfo(msg);
-	return true;
+	return TF_STAY;
 }
 
-bool replyListener(TF_MSG *msg)
+TF_Result replyListener(TF_Msg *msg)
 {
 	printf("replyListener()\n");
 	dumpFrameInfo(msg);
@@ -21,8 +21,14 @@ bool replyListener(TF_MSG *msg)
 	msg->len = (TF_LEN) strlen((const char *) msg->data);
 	TF_Respond(msg);
 
+	// unsolicted reply - will not be handled
+	msg->data = (const uint8_t *) "SPAM";
+	msg->len = 5;
+	TF_Respond(msg);
+
+	// unrelated message
 	TF_SendSimple(77, (const uint8_t *) "NAZDAR", 7);
-	return true;
+	return TF_STAY;
 }
 
 int main(void)
diff --git a/demo/test/test.c b/demo/test/test.c
index dc686cd..90c9371 100644
--- a/demo/test/test.c
+++ b/demo/test/test.c
@@ -19,22 +19,22 @@ void TF_WriteImpl(const uint8_t *buff, size_t len)
 }
 
 /** An example listener function */
-bool myListener(TF_MSG *msg)
+TF_Result myListener(TF_Msg *msg)
 {
 	dumpFrameInfo(msg);
-	return true;
+	return TF_STAY;
 }
 
-bool testIdListener(TF_MSG *msg)
+TF_Result testIdListener(TF_Msg *msg)
 {
 	printf("OK - ID Listener triggered for msg!\n");
 	dumpFrameInfo(msg);
-	return true;
+	return TF_CLOSE;
 }
 
 void main(void)
 {
-	TF_MSG msg;
+	TF_Msg msg;
 	const char *longstr = "Lorem ipsum dolor sit amet.";
 
 	// Set up the TinyFrame library
diff --git a/demo/utils.c b/demo/utils.c
index 3454cbf..2454c2c 100644
--- a/demo/utils.c
+++ b/demo/utils.c
@@ -21,7 +21,7 @@ void dumpFrame(const uint8_t *buff, size_t len)
 	printf("--- end of frame ---\n\n");
 }
 
-void dumpFrameInfo(TF_MSG *msg)
+void dumpFrameInfo(TF_Msg *msg)
 {
 	printf("\033[33mFrame info\n"
 			   "  type: %02Xh\n"
diff --git a/demo/utils.h b/demo/utils.h
index 06c4af5..f45a807 100644
--- a/demo/utils.h
+++ b/demo/utils.h
@@ -8,8 +8,19 @@
 #include <stdio.h>
 #include "../TinyFrame.h"
 
+/** pointer to unsigned char */
 typedef unsigned char* pu8;
+
+/**
+ * Dump a binary frame as hex, dec and ASCII
+ */
 void dumpFrame(const uint8_t *buff, size_t len);
-void dumpFrameInfo(TF_MSG *msg);
+
+/**
+ * Dump message metadata (not the content)
+ *
+ * @param msg
+ */
+void dumpFrameInfo(TF_Msg *msg);
 
 #endif //TF_UTILS_H