diff --git a/modules/global-db/dap_chain_global_db.c b/modules/global-db/dap_chain_global_db.c
index b10bd0088ad5a4bc590bbe431ef9ba02ebdf90a5..ab5582616ac3be4e051be1bc8e62316b5a604e6c 100644
--- a/modules/global-db/dap_chain_global_db.c
+++ b/modules/global-db/dap_chain_global_db.c
@@ -51,13 +51,13 @@
 // for access from several streams
 //static pthread_mutex_t ldb_mutex_ = PTHREAD_MUTEX_INITIALIZER;
 
-//Do nothing
+// The function does nothing
 static inline void lock()
 {
     //pthread_mutex_lock(&ldb_mutex_);
 }
 
-//Do nothing
+// The function does nothing
 static inline void unlock()
 {
     //pthread_mutex_unlock(&ldb_mutex_);
@@ -79,9 +79,11 @@ static sync_group_item_t *s_sync_group_extra_items = NULL;
 static bool s_track_history = false;
 
 /**
- * @brief dap_chain_global_db_add_sync_group
- * @details Add group name for synchronization
- * @param a_group_prefix
+ * @brief Adds a group name for synchronization.
+ * @param a_group_prefix a prefix of the group name 
+ * @param a_callback a callback function
+ * @param a_arg a pointer to an argument
+ * @return (none)
  */
 void dap_chain_global_db_add_sync_group(const char *a_group_prefix, dap_global_db_obj_callback_notify_t a_callback, void *a_arg)
 {
@@ -94,9 +96,11 @@ void dap_chain_global_db_add_sync_group(const char *a_group_prefix, dap_global_d
 }
 
 /**
- * @brief dap_chain_global_db_add_sync_extra_group
- * @details Add group name for synchronization with especially node addresses
- * @param a_group_prefix
+ * @brief Adds a group name for synchronization with especially node addresses.
+ * @param a_group_mask a group mask string
+ * @param a_callback a callabck function
+ * @param a_arg a pointer to an argument
+ * @return (none)
  */
 void dap_chain_global_db_add_sync_extra_group(const char *a_group_mask, dap_global_db_obj_callback_notify_t a_callback, void *a_arg)
 {
@@ -108,6 +112,11 @@ void dap_chain_global_db_add_sync_extra_group(const char *a_group_mask, dap_glob
     HASH_ADD_STR(s_sync_group_extra_items, group_mask, l_item);
 }
 
+/**
+ * @brief Gets a list of a group mask.
+ * @param a_table a table
+ * @return Returns a pointer to a list of a group mask.
+ */
 dap_list_t *dap_chain_db_get_sync_groups_internal(sync_group_item_t *a_table)
 {
     dap_list_t *l_ret = NULL;
@@ -118,19 +127,29 @@ dap_list_t *dap_chain_db_get_sync_groups_internal(sync_group_item_t *a_table)
     return l_ret;
 }
 
+/** 
+ * @brief Gets a list of a group mask for s_sync_group_items.
+ * @return Returns a pointer to a list of a group mask.
+ */
 dap_list_t *dap_chain_db_get_sync_groups()
 {
     return dap_chain_db_get_sync_groups_internal(s_sync_group_items);
 }
 
+/** 
+ * @brief Gets a list of a group mask for s_sync_group_items.
+ * @param a_table a table
+ * @return Returns a pointer to a list of a group mask.
+ */
 dap_list_t *dap_chain_db_get_sync_extra_groups()
 {
     return dap_chain_db_get_sync_groups_internal(s_sync_group_extra_items);
 }
 
 /**
- * @brief Deallocates memory of key and value members of a item.
- * @param obj A pointer to the item
+ * @brief Deallocates memory of a key and a value members of an obj structure.
+ * @param obj a pointer to the structure
+ * @return (none)
  */
 void dap_chain_global_db_obj_clean(dap_global_db_obj_t *obj)
 {
@@ -143,8 +162,9 @@ void dap_chain_global_db_obj_clean(dap_global_db_obj_t *obj)
 }
 
 /**
- * @brief Deallocates memory of a item.
- * @param obj A pointer to the item
+ * @brief Deallocates memory of an obj structure.
+ * @param obj a pointer to the object 
+ * @return (none)
  */
 void dap_chain_global_db_obj_delete(dap_global_db_obj_t *obj)
 {
@@ -153,9 +173,10 @@ void dap_chain_global_db_obj_delete(dap_global_db_obj_t *obj)
 }
 
 /**
- * @brief Deallocates memory of array of items.
- * @param objs an array of items
- * @param a_count A aount of items in the array.
+ * @brief Deallocates memory of an objs array.
+ * @param objs a pointer to the first object of the array
+ * @param a_count a number of objects in the array
+ * @return (none)
  */
 void dap_chain_global_db_objs_delete(dap_global_db_obj_t *objs, size_t a_count)
 {
@@ -166,9 +187,10 @@ void dap_chain_global_db_objs_delete(dap_global_db_obj_t *objs, size_t a_count)
 }
 
 /**
- * @brief Initialise a datebase. Befor using must call this fuction.
- * @param g_config a pointer to a congiguration struct
- * @return 0 if success, otherwise error,
+ * @brief Initializes a database by g_config structure. 
+ * @note You should call this function before calling any other functions in this library.
+ * @param g_config a pointer to the configuration structure
+ * @return Returns 0 if successful; otherwise, <0.
  */
 int dap_chain_global_db_init(dap_config_t * g_config)
 {
@@ -187,7 +209,9 @@ int dap_chain_global_db_init(dap_config_t * g_config)
 }
 
 /**
- * @brief Deinitialise a datebase.
+ * @brief Deinitialize a database. 
+ * @note You should call this function at the end.
+ * @return (none)
  */
 void dap_chain_global_db_deinit(void)
 {
@@ -213,7 +237,7 @@ void dap_chain_global_db_deinit(void)
 }
 
 /**
- * @brief Flushes a datebase.
+ * @brief Flushes a database cahce to disk.
  * @return 0
  */
 int dap_chain_global_db_flush(void){
@@ -224,10 +248,10 @@ int dap_chain_global_db_flush(void){
 }
 
 /**
- * @brief Gets an item from a datebase by a_key and a_group
- * @param a_key a key
- * @param a_group the group name
- * @return If successful, a pointer to an array of items, otherwise NULL.
+ * @brief Gets an object from a database by a_key and a_group arguments.
+ * @param a_key an object key string
+ * @param a_group a group name string
+ * @return If successful, returns a pointer to the item, otherwise NULL.
  */
 void* dap_chain_global_db_obj_get(const char *a_key, const char *a_group)
 {
@@ -238,11 +262,12 @@ void* dap_chain_global_db_obj_get(const char *a_key, const char *a_group)
 }
 
 /**
- * @brief dap_chain_global_db_obj_gr_get
- * @param a_key
- * @param a_data_out
- * @param a_group
- * @return
+ * @brief Gets an array consisting of a_data_len_out objects from a database by a_key and a_group arguments.
+ * @param a_key an object key string
+ * @param a_data_len_out[in] a number of objects to be gotten, if NULL - no limits
+ * @param a_data_len_out[out] a number of objects that were gotten
+ * @param a_group a group name string  
+ * @return If successful, returns a pointer to the first item in the array; otherwise NULL.
  */
 dap_store_obj_t* dap_chain_global_db_obj_gr_get(const char *a_key, size_t *a_data_len_out, const char *a_group)
 {
@@ -259,11 +284,12 @@ dap_store_obj_t* dap_chain_global_db_obj_gr_get(const char *a_key, size_t *a_dat
 }
 
 /**
- * @brief dap_chain_global_db_gr_get
- * @param a_key
- * @param a_data_out
- * @param a_group
- * @return
+ * @brief Gets an object value from database by a_key and a_group.
+ * @param a_key an object key string
+ * @param a_data_out[in] a number of objects to be gotten, if NULL - no limits
+ * @param a_data_out[out] a length of values that were gotten
+ * @param a_group a group name string
+ * @return If successful, returns a pointer to the object value.
  */
 uint8_t * dap_chain_global_db_gr_get(const char *a_key, size_t *a_data_len_out, const char *a_group)
 {
@@ -284,6 +310,13 @@ uint8_t * dap_chain_global_db_gr_get(const char *a_key, size_t *a_data_len_out,
     return l_ret_value;
 }
 
+
+/**
+ * @brief Gets an object value from database by a_key for the "local.general" group.
+ * @param a_key an object key string
+ * @param a_data_out a length of value that were gotten
+ * @return If successful, returns a pointer to the object value, otherwise NULL.
+ */
 uint8_t * dap_chain_global_db_get(const char *a_key, size_t *a_data_out)
 {
     return dap_chain_global_db_gr_get(a_key, a_data_out, GROUP_LOCAL_GENERAL);
@@ -291,7 +324,11 @@ uint8_t * dap_chain_global_db_get(const char *a_key, size_t *a_data_out)
 
 
 /**
- * Add info about the deleted entry to the base
+ * @brief Adds info about the deleted entry to the database.
+ * @param a_key an object key string
+ * @param a_group a group name string
+ * @param a_timestamp an object time stamp
+ * @return True if successful, false otherwise.
  */
 static bool global_db_gr_del_add(char *a_key,const char *a_group, time_t a_timestamp)
 {
@@ -318,12 +355,10 @@ static bool global_db_gr_del_add(char *a_key,const char *a_group, time_t a_times
 
 
 /**
- * @brief global_db_gr_del_del:
- * Delete info about the deleted entry from the base
- * @param a_key - key, looked like "0x8FAFBD00B..."
- * @param a_group - group name, for example "kelvin-testnet.nodes"
- * @return true 
- * @return false 
+ * @brief Deletes info about the deleted object from the database
+ * @param a_key an object key string, looked like "0x8FAFBD00B..."
+ * @param a_group a group name string, for example "kelvin-testnet.nodes"
+ * @return If successful, returns true; otherwise, false. 
  */
 static bool global_db_gr_del_del(char *a_key, const char *a_group)
 {
@@ -348,9 +383,9 @@ static bool global_db_gr_del_del(char *a_key, const char *a_group)
 
 
 /**
- * @brief Gets time stamp of the deleted item by a_group and a_key
- * @param a_group a group name, for example "kelvin-testnet.nodes"
- * @param a_key a key, looked like "0x8FAFBD00B..."
+ * @brief Gets time stamp of the deleted object by a_group and a_key arguments.
+ * @param a_group a group name sring, for example "kelvin-testnet.nodes"
+ * @param a_key an object key string, looked like "0x8FAFBD00B..."
  * @return If successful, a time stamp, otherwise 0.
  */
 time_t global_db_gr_del_get_timestamp(const char *a_group, char *a_key)
@@ -378,9 +413,9 @@ time_t global_db_gr_del_get_timestamp(const char *a_group, char *a_key)
 }
 
 /**
- * @brief Call dap_chain_global_db_gr_del(a_key, GROUP_LOCAL_GENERAL).
- * @param a_key key
- * @return True or false
+ * @brief Deletes item from a database by a a_key for the "local.general" group.
+ * @param a_key an object key string
+ * @return True if successful, false otherwise.
  */
 bool dap_chain_global_db_del(char *a_key)
 {
@@ -389,9 +424,9 @@ bool dap_chain_global_db_del(char *a_key)
 
 
 /**
- * @brief Gets a last item from a datebase by a_group.
- * @param a_group a group name
- * @return If successful, a pointer to item; otherwise NULL.
+ * @brief Gets a last item from a database by a_group.
+ * @param a_group a group name string
+ * @return If successful, a pointer to the object; otherwise NULL.
  */
 dap_store_obj_t* dap_chain_global_db_get_last(const char *a_group)
 {
@@ -403,12 +438,12 @@ dap_store_obj_t* dap_chain_global_db_get_last(const char *a_group)
 }
 
 /**
- * @brief Gets items from a database by a_group_name and a_first_id.
- * @param a_group a group name
+ * @brief Gets objects from a database by a_group_name and a_first_id.
+ * @param a_group a group name string
  * @param a_first_id a first id
- * @param a_objs_count[in] a count items to read, if 0 - no limits
- * @param a_objs_count[out] a count items were read
- * @return If successful, a pointer to items; otherwise NULL.
+ * @param a_objs_count[in] a number of object to be read, if 0 - no limits
+ * @param a_objs_count[out] a number of object were read
+ * @return If successful, a pointer to objects; otherwise NULL.
  */
 dap_store_obj_t* dap_chain_global_db_cond_load(const char *a_group, uint64_t a_first_id, size_t *a_objs_count)
 {
@@ -420,10 +455,10 @@ dap_store_obj_t* dap_chain_global_db_cond_load(const char *a_group, uint64_t a_f
 }
 
 /**
- * @brief Gets all data from a database by a_group
- * @param a_group a group name
- * @param a_data_size[in] a poiter to return a count of data
- * @param a_data_size[out] a count of data
+ * @brief Gets all data from a database by a_group.
+ * @param a_group a group name string
+ * @param a_data_size[in] a poiter to return a number of data
+ * @param a_data_size[out] a number of data
  * @return If successful, a pointer to data; otherwise NULL.
  */
 dap_global_db_obj_t* dap_chain_global_db_gr_load(const char *a_group, size_t *a_data_size_out)
@@ -452,7 +487,7 @@ dap_global_db_obj_t* dap_chain_global_db_gr_load(const char *a_group, size_t *a_
 }
 
 /**
- * @brief Calls a dap_chain_global_db_gr_load(GROUP_LOCAL_GENERAL, a_data_size_out).
+ * @brief Gets all data from a database for the "local.general" group
  */
 dap_global_db_obj_t* dap_chain_global_db_load(size_t *a_data_size_out)
 {
@@ -460,9 +495,10 @@ dap_global_db_obj_t* dap_chain_global_db_load(size_t *a_data_size_out)
 }
 
 /**
- * @brief Finds item by a_group
- * @param a_group
- * @return
+ * @brief Finds item by a_items and a_group 
+ * @param a_items items
+ * @param a_group a group name string
+ * @return 
  */
 static sync_group_item_t *find_item_by_mask(sync_group_item_t *a_items, const char *a_group)
 {
@@ -474,7 +510,12 @@ static sync_group_item_t *find_item_by_mask(sync_group_item_t *a_items, const ch
     return NULL;
 }
 
-
+/**
+ * @brief Adds data to the history log
+ * 
+ * @param a_store_data a pointer to an object
+ * @return (none)
+ */
 void dap_global_db_obj_track_history(void* a_store_data)
 {
     dap_store_obj_t *l_obj = (dap_store_obj_t *)a_store_data;
@@ -519,13 +560,13 @@ void dap_global_db_obj_track_history(void* a_store_data)
 
 
 /**
- * @brief Adds a value to a datebase.
- * @param a_key a key
+ * @brief Adds a value to a database.
+ * @param a_key a object key string
  * @param a_value a value to be added
- * @param a_value_len length of value. If a_value_len=-1, counts it in function
- * @param a_group a group name
+ * @param a_value_len length of value. If a_value_len=-1, the function calculates length.
+ * @param a_group a group name string
  * @details Set one entry to base. IMPORTANT: a_key and a_value should be passed without free after (it will be released by gdb itself)
- * @return
+ * @return True if successful, false otherwise.
  */
 bool dap_chain_global_db_gr_set(char *a_key, void *a_value, size_t a_value_len, const char *a_group)
 {
@@ -557,18 +598,21 @@ bool dap_chain_global_db_gr_set(char *a_key, void *a_value, size_t a_value_len,
 }
 
 /**
- * @breif Calls dap_chain_global_db_gr_set(a_key, a_value, a_value_len, GROUP_LOCAL_GENERAL)
+ * @brief Adds a value to a database for the "local.general" group
+ * @param a_value a value to be added
+ * @param a_value_len length of value. If a_value_len=-1, the function counts length.
+ * @return True if successful, false otherwise.
  */
 bool dap_chain_global_db_set( char *a_key,  void *a_value, size_t a_value_len)
 {
     return dap_chain_global_db_gr_set(a_key, a_value, a_value_len, GROUP_LOCAL_GENERAL);
 }
 
-/**
- * @brief Deletes item from a datebase by a a_key and a_group.
- * @param a_key a key
- * @param a_group a group name
- * @return True or false.
+/** 
+ * @brief Deletes object from a database by a a_key and a_group arguments.
+ * @param a_key a object key string
+ * @param a_group a group name string
+ * @return True if object was deleted or false otherwise.
  */
 bool dap_chain_global_db_gr_del(char *a_key,const char *a_group)
 {
@@ -596,10 +640,10 @@ bool dap_chain_global_db_gr_del(char *a_key,const char *a_group)
 }
 
 /**
- * @brief Saves(deletes) items to a database from an array of data_size bytes
- * @param a_store_data a pointer to data
- * @param a_objs_count a count of items
- * @return True or false.
+ * @brief Saves(deletes) objects to (from) a database.
+ * @param a_store_data a pointer to objects
+ * @param a_objs_count a number of objects
+ * @return True if object was deleted or false otherwise.
  */
 bool dap_chain_global_db_obj_save(void* a_store_data, size_t a_objs_count)
 {
@@ -640,10 +684,10 @@ bool dap_chain_global_db_obj_save(void* a_store_data, size_t a_objs_count)
 }
 
 /**
- * @brief Saves items in a datebase by a_group.
- * @param a_objs a pointer to items
- * @param a_objs_count a count of items
- * @param a_group a group name
+ * @brief Saves objects in a database by a_group.
+ * @param a_objs a pointer to objects
+ * @param a_objs_count a number of objects
+ * @param a_group a group name string
  * @return If successful, true; otherwise false.
  */
 bool dap_chain_global_db_gr_save(dap_global_db_obj_t* a_objs, size_t a_objs_count, const char *a_group)
@@ -667,9 +711,9 @@ bool dap_chain_global_db_gr_save(dap_global_db_obj_t* a_objs, size_t a_objs_coun
 }
 
 /**
- * @brief Saves items in a database.
- * @param a_objs a pointer to items
- * @param a_objs_count a count of items
+ * @brief Saves objectss in a database.
+ * @param a_objs a pointer to objects
+ * @param a_objs_count a number of objects
  * @return If successful, true; otherwise false.
  */
 bool dap_chain_global_db_save(dap_global_db_obj_t* a_objs, size_t a_objs_count)
diff --git a/modules/global-db/dap_chain_global_db_driver.c b/modules/global-db/dap_chain_global_db_driver.c
index fba9c6dd17d67ba9343cc6d00c116259eb9b8f38..f019bd15c818efe0944484ceacc14c16b258f877 100644
--- a/modules/global-db/dap_chain_global_db_driver.c
+++ b/modules/global-db/dap_chain_global_db_driver.c
@@ -43,7 +43,7 @@
 
 #define LOG_TAG "db_driver"
 
-// A selected datebase driver.
+// A selected database driver.
 static char *s_used_driver = NULL;
 
 //#define USE_WRITE_BUFFER
@@ -73,11 +73,12 @@ static void* func_write_buf(void * arg);
 static dap_db_driver_callbacks_t s_drv_callback;
 
 /**
- * @brief Initializes a database driver. Befor using the driver must call this fuction.
- * @param driver_name a string determining a type of datebase driver. 
- * Maybe "сdb", "sqlite" ("sqlite3"), "pgsql", "mdbx"
- * @param a_filename_db a name of a datebase file
- * @return If successful, 0 , otherwise <0.
+ * @brief Initializes a database driver. 
+ * @note You should Call this function before using the driver.
+ * @param driver_name a string determining a type of database driver:
+ * "сdb", "sqlite" ("sqlite3") or "pgsql"
+ * @param a_filename_db a path to a database file
+ * @return Returns 0, if successful; otherwise <0.
  */
 int dap_db_driver_init(const char *a_driver_name, const char *a_filename_db)
 {
@@ -129,7 +130,9 @@ int dap_db_driver_init(const char *a_driver_name, const char *a_filename_db)
 }
 
 /**
- * @brief Deinitializes a database driver. Must call this function after using the driver.
+ * @brief Deinitializes a database driver.
+ * @note You should call this function after using the driver.
+ * @return (none)
  */
 void dap_db_driver_deinit(void)
 {
@@ -170,8 +173,8 @@ void dap_db_driver_deinit(void)
 }
 
 /**
- * @brief Flush data to disk
- * @return 0
+ * @brief Flushes a database cahce to disk.
+ * @return Returns 0, if successful; otherwise <0.
  */
 int dap_db_driver_flush(void)
 {
@@ -179,10 +182,10 @@ int dap_db_driver_flush(void)
 }
 
 /**
- * @brief Copies a_store_count items from a_store_obj to return.
- * @param a_store_obj a pointer to source items
- * @param a_store_count a count of items
- * @return A pointer to the copied items.
+ * @brief Copies objects from a_store_obj.
+ * @param a_store_obj a pointer to the source objects
+ * @param a_store_count a number of objects
+ * @return A pointer to the copied objects.
  */
 dap_store_obj_t* dap_store_obj_copy(dap_store_obj_t *a_store_obj, size_t a_store_count)
 {
@@ -202,9 +205,9 @@ dap_store_obj_t* dap_store_obj_copy(dap_store_obj_t *a_store_obj, size_t a_store
 }
 
 /**
- * @brief Deallocates memory of items.
- * @param a_store_obj a pointer to items
- * @param a_store_count a count of items
+ * @brief Deallocates memory of objects.
+ * @param a_store_obj a pointer to objects
+ * @param a_store_count a number of objects
  * @return (none)
  */
 void dap_store_obj_free(dap_store_obj_t *a_store_obj, size_t a_store_count)
@@ -221,10 +224,10 @@ void dap_store_obj_free(dap_store_obj_t *a_store_obj, size_t a_store_count)
 }
 
 /**
- * @brief Calcs hash string for data
+ * @brief Calculates a hash of data.
  * @param data a pointer to data
  * @param data_size a size of data
- * @return Hash string or NULL.
+ * @return Returns a hash string if successful; otherwise NULL.
  */
 char* dap_chain_global_db_driver_hash(const uint8_t *data, size_t data_size)
 {
@@ -244,11 +247,11 @@ char* dap_chain_global_db_driver_hash(const uint8_t *data, size_t data_size)
 }
 
 /**
- * @brief Wait data to write buffer
+ * @brief Waits for a buffer to be written.
  * @param a_mutex a mutex
- * @param a_cond condition
+ * @param a_cond a condition
  * @param l_timeout_ms timeout in ms, if -1 endless waiting
- * @return 0 - Ok, 1 - timeout
+ * @return Returns 0 if successful or 1 when the timeout is due.
  */
 static int wait_data(pthread_mutex_t *a_mutex, pthread_cond_t *a_cond, int l_timeout_ms)
 {
@@ -280,8 +283,8 @@ static int wait_data(pthread_mutex_t *a_mutex, pthread_cond_t *a_cond, int l_tim
 #ifdef USE_WRITE_BUFFER
 /
 /**
- * @brief Checks buffer is fill
- * @return 0 if buffer empty, 1 data present
+ * @brief Checks if a buffer is not empty.
+ * @return Returns true if the buffer is not empty, false if it is empty.
  */
 static bool check_fill_buf(void)
 {
@@ -301,7 +304,8 @@ static bool check_fill_buf(void)
 }
 
 /**
- * @brief Waits apply write buffer.
+ * @brief Waits until the buffer is not empty.
+ * @return (none)
  */
 static void wait_write_buf()
 {
@@ -317,7 +321,7 @@ static void wait_write_buf()
 }
 
 /**
- * @brief Saves data from buffer to database
+ * @brief Saves data from a buffer to a database.
  * @return 0
  */
 static int save_write_buf(void)
@@ -379,8 +383,8 @@ static int save_write_buf(void)
 }
 
 /**
- * @brief thread for save data from buffer to database
- * @param arg
+ * @brief A thread for saving data from buffer to a database
+ * @param arg NULL, is not used
  * @return NULL
  */
 static void* func_write_buf(void * arg)
@@ -401,10 +405,10 @@ static void* func_write_buf(void * arg)
 #endif //USE_WRITE_BUFFER
 
 /**
- * @brief Applies items to datebase
- * @param a_store an array of items
- * @param a_store_count a count of items
- * @return 
+ * @brief Applies objects to database.
+ * @param a_store an pointer to the objects
+ * @param a_store_count a number of objectss
+ * @return Returns 0, if successful.
  */
 int dap_chain_global_db_driver_appy(pdap_store_obj_t a_store_obj, size_t a_store_count)
 {
@@ -467,10 +471,10 @@ int dap_chain_global_db_driver_appy(pdap_store_obj_t a_store_obj, size_t a_store
 }
 
 /**
- * @brief Adds items to a database.
- * @param a_store_obj items to be added
- * @param a_store_count a count added items
- * @return If sucseesful, 1, otherwise 0 or <0.
+ * @brief Adds objects to a database.
+ * @param a_store_obj objects to be added
+ * @param a_store_count a number of added objects
+ * @return Returns 0 if sucseesful.
  */
 int dap_chain_global_db_driver_add(pdap_store_obj_t a_store_obj, size_t a_store_count)
 {
@@ -480,10 +484,10 @@ int dap_chain_global_db_driver_add(pdap_store_obj_t a_store_obj, size_t a_store_
 }
 
 /**
- * @brief Deletes items from a database.
- * @param a_store_obj items to be deleted
- * @param a_store_count a count deleted items
- * @return If sucseesful, 1, otherwise 0 or <0.
+ * @brief Deletes objects from a database.
+ * @param a_store_obj objects to be deleted
+ * @param a_store_count a number of deleted objects
+ * @return Returns 0 if sucseesful.
  */
 int dap_chain_global_db_driver_delete(pdap_store_obj_t a_store_obj, size_t a_store_count)
 {
@@ -493,10 +497,10 @@ int dap_chain_global_db_driver_delete(pdap_store_obj_t a_store_obj, size_t a_sto
 }
 
 /**
- * @brief Gets a count of items in a database by a_group and id.
- * @param a_group the group name
+ * @brief Gets a number of stored objects in a database by a_group and id.
+ * @param a_group the group name string
  * @param a_id id
- * @return The count of items.
+ * @return Returns a number of objects.
  */
 size_t dap_chain_global_db_driver_count(const char *a_group, uint64_t id)
 {
@@ -511,8 +515,8 @@ size_t dap_chain_global_db_driver_count(const char *a_group, uint64_t id)
  * @brief Gets a list of group names matching the pattern.
  * Check whether the groups match the pattern a_group_mask, which is a shell wildcard pattern
  * patterns: [] {} [!] * ? https://en.wikipedia.org/wiki/Glob_(programming).
- * @param a_group_mask the group mask
- * @return If successful, the list of group names, otherwise NULL.
+ * @param a_group_mask the group mask string
+ * @return If successful, returns the list of group names, otherwise NULL.
  */
 dap_list_t* dap_chain_global_db_driver_get_groups_by_mask(const char *a_group_mask)
 {
@@ -524,9 +528,9 @@ dap_list_t* dap_chain_global_db_driver_get_groups_by_mask(const char *a_group_ma
 
 
 /**
- * @brief Reads last items in the database.
+ * @brief Reads last object in the database.
  * @param a_group the group name
- * @return If successful, a pointer to the item, otherwise NULL.
+ * @return If successful, a pointer to the object, otherwise NULL.
  */
 dap_store_obj_t* dap_chain_global_db_driver_read_last(const char *a_group)
 {
@@ -542,12 +546,12 @@ dap_store_obj_t* dap_chain_global_db_driver_read_last(const char *a_group)
 }
 
 /**
- * @brief Reads several items from a database by a_group and id.
- * @param a_group the group name
+ * @brief Reads several objects from a database by a_group and id.
+ * @param a_group the group name string
  * @param a_id id
- * @param a_count_out[in] a count of items to read, if 0 - no limits
- * @param a_count_out[out] a count of items were read
- * @return If successful, a pointer to an array of items, otherwise NULL.
+ * @param a_count_out[in] a number of objects to be read, if 0 - no limits
+ * @param a_count_out[out] a count of objects that were read
+ * @return If successful, a pointer to an objects, otherwise NULL.
  */
 dap_store_obj_t* dap_chain_global_db_driver_cond_read(const char *a_group, uint64_t id, size_t *a_count_out)
 {
@@ -563,13 +567,13 @@ dap_store_obj_t* dap_chain_global_db_driver_cond_read(const char *a_group, uint6
 }
 
 /**
- * @brief Reads several items from a database by a_group and a_key.
+ * @brief Reads several objects from a database by a_group and a_key.
  * If a_key is NULL, reads whole group.
- * @param a_group the group name
- * @param a_key  key name, may by NULL. it means reading the whole group
- * @param a_count_out[in] a count of items to read, if 0 - no limits
- * @param a_count_out[out] a count of items was read
- * @return If successful, a pointer to an array of items, otherwise NULL.
+ * @param a_group a group name string
+ * @param a_key  an object key string. If equal NULL, it means reading the whole group
+ * @param a_count_out[in] a number of objects to be read, if 0 - no limits
+ * @param a_count_out[out] a number of objects that were read
+ * @return If successful, a pointer to an objects, otherwise NULL.
  */
 dap_store_obj_t* dap_chain_global_db_driver_read(const char *a_group, const char *a_key, size_t *a_count_out)
 {
@@ -585,10 +589,10 @@ dap_store_obj_t* dap_chain_global_db_driver_read(const char *a_group, const char
 }
 
 /**
- * @brief Checks an element in a database by a_group and a_key.
- * @param a_group a group namme
- * @param a_key a key
- * @return True if is, 0 otherwise.
+ * @brief Checks if an object is in a database by a_group and a_key.
+ * @param a_group a group name string
+ * @param a_key a object key string
+ * @return Returns true if it is, false otherwise.
  */
 bool dap_chain_global_db_driver_is(const char *a_group, const char *a_key)
 {