diff --git a/apps/er-coap-07/er-coap-07-engine.c b/apps/er-coap-07/er-coap-07-engine.c
index 875db015e..a65262172 100644
--- a/apps/er-coap-07/er-coap-07-engine.c
+++ b/apps/er-coap-07/er-coap-07-engine.c
@@ -102,7 +102,7 @@ handle_incoming_data(void)
 
       /*TODO duplicates suppression, if required */
 
-      PRINTF("  Parsed: v %u, t %u, oc %u, c %u, tid %u\n", message->version, message->type, message->option_count, message->code, message->tid);
+      PRINTF("  Parsed: v %u, t %u, oc %u, c %u, mid %u\n", message->version, message->type, message->option_count, message->code, message->mid);
       PRINTF("  URL: %.*s\n", message->uri_path_len, message->uri_path);
       PRINTF("  Payload: %.*s\n", message->payload_len, message->payload);
 
@@ -110,7 +110,7 @@ handle_incoming_data(void)
       if (message->code >= COAP_GET && message->code <= COAP_DELETE)
       {
         /* Use transaction buffer for response to confirmable request. */
-        if ( (transaction = coap_new_transaction(message->tid, &UIP_IP_BUF->srcipaddr, UIP_UDP_BUF->srcport)) )
+        if ( (transaction = coap_new_transaction(message->mid, &UIP_IP_BUF->srcipaddr, UIP_UDP_BUF->srcport)) )
         {
           static uint32_t block_num = 0;
           static uint16_t block_size = REST_MAX_CHUNK_SIZE;
@@ -121,12 +121,12 @@ handle_incoming_data(void)
           if (message->type==COAP_TYPE_CON)
           {
             /* Reliable CON requests are answered with an ACK. */
-            coap_init_message(response, COAP_TYPE_ACK, CONTENT_2_05, message->tid);
+            coap_init_message(response, COAP_TYPE_ACK, CONTENT_2_05, message->mid);
           }
           else
           {
             /* Unreliable NON requests are answered with a NON as well. */
-            coap_init_message(response, COAP_TYPE_NON, CONTENT_2_05, coap_get_tid());
+            coap_init_message(response, COAP_TYPE_NON, CONTENT_2_05, coap_get_mid());
           }
 
           /* resource handlers must take care of different handling (e.g., TOKEN_OPTION_REQUIRED_240) */
@@ -228,7 +228,7 @@ handle_incoming_data(void)
           }
         }
 
-        if ( (transaction = coap_get_transaction_by_tid(message->tid)) )
+        if ( (transaction = coap_get_transaction_by_mid(message->mid)) )
         {
           /* Free transaction memory before callback, as it may create a new transaction. */
           restful_response_handler callback = transaction->callback;
@@ -258,7 +258,7 @@ handle_incoming_data(void)
         coap_error_code = INTERNAL_SERVER_ERROR_5_00;
       }
       /* Reuse input buffer for error message. */
-      coap_init_message(message, COAP_TYPE_ACK, coap_error_code, message->tid);
+      coap_init_message(message, COAP_TYPE_ACK, coap_error_code, message->mid);
       coap_set_payload(message, coap_error_message, strlen(coap_error_message));
       coap_send_message(&UIP_IP_BUF->srcipaddr, UIP_UDP_BUF->srcport, uip_appdata, coap_serialize_message(message, uip_appdata));
     }
@@ -462,8 +462,8 @@ PT_THREAD(coap_blocking_request(struct request_state_t *state, process_event_t e
   block_error = 0;
 
   do {
-    request->tid = coap_get_tid();
-    if ((state->transaction = coap_new_transaction(request->tid, remote_ipaddr, remote_port)))
+    request->mid = coap_get_mid();
+    if ((state->transaction = coap_new_transaction(request->mid, remote_ipaddr, remote_port)))
     {
       state->transaction->callback = blocking_request_callback;
       state->transaction->callback_data = state;
@@ -476,7 +476,7 @@ PT_THREAD(coap_blocking_request(struct request_state_t *state, process_event_t e
       state->transaction->packet_len = coap_serialize_message(request, state->transaction->packet);
 
       coap_send_transaction(state->transaction);
-      PRINTF("Requested #%lu (TID %u)\n", state->block_num, request->tid);
+      PRINTF("Requested #%lu (MID %u)\n", state->block_num, request->mid);
 
       PT_YIELD_UNTIL(&state->pt, ev == PROCESS_EVENT_POLL);
 
diff --git a/apps/er-coap-07/er-coap-07-observing.c b/apps/er-coap-07/er-coap-07-observing.c
index 5ef27f024..042358ded 100644
--- a/apps/er-coap-07/er-coap-07-observing.c
+++ b/apps/er-coap-07/er-coap-07-observing.c
@@ -154,7 +154,7 @@ coap_notify_observers(const char *url, int type, uint32_t observe, uint8_t *payl
 
       /*TODO implement special transaction for CON, sharing the same buffer to allow for more observers */
 
-      if ( (transaction = coap_new_transaction(coap_get_tid(), &obs->addr, obs->port)) )
+      if ( (transaction = coap_new_transaction(coap_get_mid(), &obs->addr, obs->port)) )
       {
         /* Use CON to check whether client is still there/interested after COAP_OBSERVING_REFRESH_INTERVAL. */
         if (stimer_expired(&obs->refresh_timer))
@@ -166,7 +166,7 @@ coap_notify_observers(const char *url, int type, uint32_t observe, uint8_t *payl
 
         /* prepare response */
         coap_packet_t push[1]; /* This way the packet can be treated as pointer as usual. */
-        coap_init_message(push, (coap_message_type_t)type, CONTENT_2_05, transaction->tid );
+        coap_init_message(push, (coap_message_type_t)type, CONTENT_2_05, transaction->mid );
         coap_set_header_observe(push, observe);
         coap_set_header_token(push, obs->token, obs->token_len);
         coap_set_payload(push, payload, payload_len);
diff --git a/apps/er-coap-07/er-coap-07-separate.c b/apps/er-coap-07/er-coap-07-separate.c
index ef6266dbf..4377de7a2 100644
--- a/apps/er-coap-07/er-coap-07-separate.c
+++ b/apps/er-coap-07/er-coap-07-separate.c
@@ -62,11 +62,11 @@ void coap_separate_handler(resource_t *resource, void *request, void *response)
   /* send separate ACK. */
   coap_packet_t ack[1];
   /* ACK with empty code (0) */
-  coap_init_message(ack, COAP_TYPE_ACK, 0, coap_req->tid);
+  coap_init_message(ack, COAP_TYPE_ACK, 0, coap_req->mid);
   /* Should only overwrite Header which is already parsed to request. */
   coap_send_message(&UIP_IP_BUF->srcipaddr, UIP_UDP_BUF->srcport, (uip_appdata + uip_ext_len), coap_serialize_message(ack, (uip_appdata + uip_ext_len)));
 
   /* Change response to separate response. */
   coap_res->type = COAP_TYPE_CON;
-  coap_res->tid = coap_get_tid();
+  coap_res->mid = coap_get_mid();
 }
diff --git a/apps/er-coap-07/er-coap-07-transactions.c b/apps/er-coap-07/er-coap-07-transactions.c
index 739fd746a..5b56cd477 100644
--- a/apps/er-coap-07/er-coap-07-transactions.c
+++ b/apps/er-coap-07/er-coap-07-transactions.c
@@ -75,13 +75,13 @@ coap_register_as_transaction_handler()
 }
 
 coap_transaction_t *
-coap_new_transaction(uint16_t tid, uip_ipaddr_t *addr, uint16_t port)
+coap_new_transaction(uint16_t mid, uip_ipaddr_t *addr, uint16_t port)
 {
   coap_transaction_t *t = memb_alloc(&transactions_memb);
 
   if (t)
   {
-    t->tid = tid;
+    t->mid = mid;
     t->retrans_counter = 0;
 
     /* save client address */
@@ -95,7 +95,7 @@ coap_new_transaction(uint16_t tid, uip_ipaddr_t *addr, uint16_t port)
 void
 coap_send_transaction(coap_transaction_t *t)
 {
-  PRINTF("Sending transaction %u\n", t->tid);
+  PRINTF("Sending transaction %u\n", t->mid);
 
   coap_send_message(&t->addr, t->port, t->packet, t->packet_len);
 
@@ -103,7 +103,7 @@ coap_send_transaction(coap_transaction_t *t)
   {
     if (t->retrans_counter<COAP_MAX_RETRANSMIT)
     {
-      PRINTF("Keeping transaction %u\n", t->tid);
+      PRINTF("Keeping transaction %u\n", t->mid);
 
       if (t->retrans_counter==0)
       {
@@ -154,7 +154,7 @@ coap_clear_transaction(coap_transaction_t *t)
 {
   if (t)
   {
-    PRINTF("Freeing transaction %u: %p\n", t->tid, t);
+    PRINTF("Freeing transaction %u: %p\n", t->mid, t);
 
     etimer_stop(&t->retrans_timer);
     list_remove(transactions_list, t);
@@ -163,15 +163,15 @@ coap_clear_transaction(coap_transaction_t *t)
 }
 
 coap_transaction_t *
-coap_get_transaction_by_tid(uint16_t tid)
+coap_get_transaction_by_mid(uint16_t mid)
 {
   coap_transaction_t *t = NULL;
 
   for (t = (coap_transaction_t*)list_head(transactions_list); t; t = t->next)
   {
-    if (t->tid==tid)
+    if (t->mid==mid)
     {
-      PRINTF("Found transaction for TID %u: %p\n", t->tid, t);
+      PRINTF("Found transaction for MID %u: %p\n", t->mid, t);
       return t;
     }
   }
@@ -188,7 +188,7 @@ coap_check_transactions()
     if (etimer_expired(&t->retrans_timer))
     {
       ++(t->retrans_counter);
-      PRINTF("Retransmitting %u (%u)\n", t->tid, t->retrans_counter);
+      PRINTF("Retransmitting %u (%u)\n", t->mid, t->retrans_counter);
       coap_send_transaction(t);
     }
   }
diff --git a/apps/er-coap-07/er-coap-07-transactions.h b/apps/er-coap-07/er-coap-07-transactions.h
index e78a2ef55..0301ec13d 100644
--- a/apps/er-coap-07/er-coap-07-transactions.h
+++ b/apps/er-coap-07/er-coap-07-transactions.h
@@ -52,7 +52,7 @@
 typedef struct coap_transaction {
   struct coap_transaction *next; /* for LIST */
 
-  uint16_t tid;
+  uint16_t mid;
   struct etimer retrans_timer;
   uint8_t retrans_counter;
 
@@ -68,10 +68,10 @@ typedef struct coap_transaction {
 
 void coap_register_as_transaction_handler();
 
-coap_transaction_t *coap_new_transaction(uint16_t tid, uip_ipaddr_t *addr, uint16_t port);
+coap_transaction_t *coap_new_transaction(uint16_t mid, uip_ipaddr_t *addr, uint16_t port);
 void coap_send_transaction(coap_transaction_t *t);
 void coap_clear_transaction(coap_transaction_t *t);
-coap_transaction_t *coap_get_transaction_by_tid(uint16_t tid);
+coap_transaction_t *coap_get_transaction_by_mid(uint16_t mid);
 
 void coap_check_transactions();
 
diff --git a/apps/er-coap-07/er-coap-07.c b/apps/er-coap-07/er-coap-07.c
index 895a6e587..3745f722f 100644
--- a/apps/er-coap-07/er-coap-07.c
+++ b/apps/er-coap-07/er-coap-07.c
@@ -61,7 +61,7 @@
 /*- Variables -----------------------------------------------------------------------*/
 /*-----------------------------------------------------------------------------------*/
 static struct uip_udp_conn *udp_conn = NULL;
-static uint16_t current_tid = 0;
+static uint16_t current_mid = 0;
 
 coap_status_t coap_error_code = NO_ERROR;
 char *coap_error_message = "";
@@ -274,19 +274,19 @@ coap_init_connection(uint16_t port)
   PRINTF("Listening on port %u\n", uip_ntohs(udp_conn->lport));
 
   /* Initialize transaction ID. */
-  current_tid = random_rand();
+  current_mid = random_rand();
 }
 /*-----------------------------------------------------------------------------------*/
 uint16_t
-coap_get_tid()
+coap_get_mid()
 {
-  return ++current_tid;
+  return ++current_mid;
 }
 /*-----------------------------------------------------------------------------------*/
 /*- MEASSAGE PROCESSING -------------------------------------------------------------*/
 /*-----------------------------------------------------------------------------------*/
 void
-coap_init_message(void *packet, coap_message_type_t type, uint8_t code, uint16_t tid)
+coap_init_message(void *packet, coap_message_type_t type, uint8_t code, uint16_t mid)
 {
   coap_packet_t *const coap_pkt = (coap_packet_t *) packet;
 
@@ -295,7 +295,7 @@ coap_init_message(void *packet, coap_message_type_t type, uint8_t code, uint16_t
 
   coap_pkt->type = type;
   coap_pkt->code = code;
-  coap_pkt->tid = tid;
+  coap_pkt->mid = mid;
 }
 /*-----------------------------------------------------------------------------------*/
 size_t
@@ -508,8 +508,8 @@ coap_serialize_message(void *packet, uint8_t *buffer)
   coap_pkt->buffer[0] |= COAP_HEADER_TYPE_MASK & (coap_pkt->type)<<COAP_HEADER_TYPE_POSITION;
   coap_pkt->buffer[0] |= COAP_HEADER_OPTION_COUNT_MASK & (coap_pkt->option_count)<<COAP_HEADER_OPTION_COUNT_POSITION;
   coap_pkt->buffer[1] = coap_pkt->code;
-  coap_pkt->buffer[2] = 0xFF & (coap_pkt->tid)>>8;
-  coap_pkt->buffer[3] = 0xFF & coap_pkt->tid;
+  coap_pkt->buffer[2] = 0xFF & (coap_pkt->mid)>>8;
+  coap_pkt->buffer[3] = 0xFF & coap_pkt->mid;
 
   PRINTF("-Done %u options, header len %u, payload len %u-\n", coap_pkt->option_count, option - buffer, coap_pkt->payload_len);
 
@@ -547,7 +547,7 @@ coap_parse_message(void *packet, uint8_t *data, uint16_t data_len)
   coap_pkt->type = (COAP_HEADER_TYPE_MASK & coap_pkt->buffer[0])>>COAP_HEADER_TYPE_POSITION;
   coap_pkt->option_count = (COAP_HEADER_OPTION_COUNT_MASK & coap_pkt->buffer[0])>>COAP_HEADER_OPTION_COUNT_POSITION;
   coap_pkt->code = coap_pkt->buffer[1];
-  coap_pkt->tid = coap_pkt->buffer[2]<<8 | coap_pkt->buffer[3];
+  coap_pkt->mid = coap_pkt->buffer[2]<<8 | coap_pkt->buffer[3];
 
   if (coap_pkt->version != 1)
   {
diff --git a/apps/er-coap-07/er-coap-07.h b/apps/er-coap-07/er-coap-07.h
index d7aead6d5..2346765da 100644
--- a/apps/er-coap-07/er-coap-07.h
+++ b/apps/er-coap-07/er-coap-07.h
@@ -54,7 +54,7 @@
 #define COAP_RESPONSE_RANDOM_FACTOR          1.5
 #define COAP_MAX_RETRANSMIT                  4
 
-#define COAP_HEADER_LEN                      4 /* | oc:0xF0 type:0x0C version:0x03 | code | tid:0x00FF | tid:0xFF00 | */
+#define COAP_HEADER_LEN                      4 /* | oc:0xF0 type:0x0C version:0x03 | code | mid:0x00FF | mid:0xFF00 | */
 #define COAP_ETAG_LEN                        8 /* The maximum number of bytes for the ETag */
 #define COAP_TOKEN_LEN                       8 /* The maximum number of bytes for the Token */
 #define COAP_MAX_ACCEPT_NUM                  2 /* The maximum number of accept preferences to parse/store */
@@ -206,7 +206,7 @@ typedef struct {
   coap_message_type_t type;
   uint8_t option_count;
   uint8_t code;
-  uint16_t tid;
+  uint16_t mid;
 
   uint32_t options;  /* Bitmap to check if option is set */
 
@@ -255,9 +255,9 @@ extern coap_status_t coap_error_code;
 extern char *coap_error_message;
 
 void coap_init_connection(uint16_t port);
-uint16_t coap_get_tid(void);
+uint16_t coap_get_mid(void);
 
-void coap_init_message(void *packet, coap_message_type_t type, uint8_t code, uint16_t tid);
+void coap_init_message(void *packet, coap_message_type_t type, uint8_t code, uint16_t mid);
 size_t coap_serialize_message(void *packet, uint8_t *buffer);
 void coap_send_message(uip_ipaddr_t *addr, uint16_t port, uint8_t *data, uint16_t length);
 coap_status_t coap_parse_message(void *request, uint8_t *data, uint16_t data_len);