diff --git a/src/sdp_client.h b/src/sdp_client.h
index 1c90b63a1..28ca46447 100644
--- a/src/sdp_client.h
+++ b/src/sdp_client.h
@@ -40,6 +40,8 @@
 
 #include <btstack/utils.h>
 
+/* SDP Client */
+ 
 /* Queries the SDP service of the remote device given a service search pattern 
 and a list of attribute IDs. The remote data is handled by the SDP parser. The 
 SDP parser delivers attribute values and done event via a registered callback. */
diff --git a/src/sdp_parser.h b/src/sdp_parser.h
index b0081b82c..b5bf77f6a 100644
--- a/src/sdp_parser.h
+++ b/src/sdp_parser.h
@@ -45,6 +45,7 @@
 
 #include <btstack/sdp_util.h>
 
+/* SDP Parser */
 
 // Data Element stream parser helper
 typedef struct de_state {
@@ -78,7 +79,7 @@ typedef struct sdp_parser_attribute_value_event {
     uint8_t data;
 } sdp_parser_attribute_value_event_t;
 
-// SDP Parser event to indicate that processing is complete
+// SDP Parser event to indicate that parsing is complete.
 typedef struct sdp_parser_complete_event {
     uint8_t type;
     uint8_t status; // 0 == OK
@@ -89,5 +90,5 @@ void sdp_parser_init();
 void sdp_parser_handle_chunk(uint8_t * data, uint16_t size);
 void sdp_parser_handle_done(uint8_t status);
 
-// Registers a callback to receive attribute value data and done event.
+// Registers a callback to receive attribute value data and parse complete event.
 void sdp_parser_register_callback(void (*sdp_callback)(sdp_parser_event_t* event));
diff --git a/src/sdp_query_rfcomm.h b/src/sdp_query_rfcomm.h
index 16cdebbae..b4f59b006 100644
--- a/src/sdp_query_rfcomm.h
+++ b/src/sdp_query_rfcomm.h
@@ -41,6 +41,8 @@
 #include <btstack/utils.h>
 #include "sdp_parser.h"
 
+/* SDP Queries */
+
 // Basic SDP Query event type
 typedef struct sdp_query_event {
     uint8_t type;
@@ -52,7 +54,11 @@ typedef struct sdp_query_complete_event {
     uint8_t status; // 0 == OK
 } sdp_query_complete_event_t;
 
-// SDP Query RFCOMM event to deliver channel number and service name byte by byte.
+
+/* SDP Query for RFCOMM */
+
+// SDP Query RFCOMM event to deliver channel number and service name
+// byte by byte.
 typedef struct sdp_query_rfcomm_service_event {
     uint8_t type;
     uint8_t channel_nr;
@@ -62,11 +68,13 @@ typedef struct sdp_query_rfcomm_service_event {
 
 void sdp_query_rfcomm_init(void);
 
-// Searches SDP records on a remote device for RFCOMM services with the given UUID.
+// Searches SDP records on a remote device for RFCOMM services with
+// a given UUID.
 void sdp_query_rfcomm_channel_and_name_for_uuid(bd_addr_t remote, uint16_t uuid);
 
-// Searches SDP records on a remote device for RFCOMM services with a given service search pattern.
+// Searches SDP records on a remote device for RFCOMM services with
+// a given service search pattern.
 void sdp_query_rfcomm_channel_and_name_for_search_pattern(bd_addr_t remote, uint8_t * des_serviceSearchPattern);
 
-// Registers a callback to receive RFCOMM service and done event. 
+// Registers a callback to receive RFCOMM service and query complete event. 
 void sdp_query_rfcomm_register_callback(void(*sdp_app_callback)(sdp_query_event_t * event, void * context), void * context);