diff --git a/dsdl/uavcan/protocol/0.GlobalTimeSync.uavcan b/dsdl/uavcan/protocol/0.GlobalTimeSync.uavcan
index d85fd3232b..40e3dd472b 100644
--- a/dsdl/uavcan/protocol/0.GlobalTimeSync.uavcan
+++ b/dsdl/uavcan/protocol/0.GlobalTimeSync.uavcan
@@ -1,15 +1,17 @@
 #
 # Global time synchronization.
-# Should be UTC time, not GPS time nor local time.
+# Preferred time is UTC.
 # Any node that publishes timestamped data must use this time reference.
 # This message is not intended for unicast transfers.
 #
+# Please refer to the specification to learn about time synchronization algorithm.
+#
 
-uint16 MAX_PUBLICATION_PERIOD_MS = 1100
-uint16 MIN_PUBLICATION_PERIOD_MS = 350
+uint16 MAX_PUBLICATION_PERIOD_MS = 1100 # Milliseconds
+uint16 MIN_PUBLICATION_PERIOD_MS = 350  # Milliseconds
 
-uint16 PUBLISHER_TIMEOUT_MS = 10000
+uint16 PUBLISHER_TIMEOUT_MS = 10000     # Milliseconds
 
-# UTC time in microseconds when the PREVIOUS GlobalTimeSync message was transmitted.
+# Time in microseconds when the PREVIOUS GlobalTimeSync message was transmitted.
 # If this message is the first one, this field must be zero.
-uint64 prev_utc_usec
+uint64 previous_transmission_timestamp_usec # Microseconds
diff --git a/libuavcan/src/protocol/uc_global_time_sync_master.cpp b/libuavcan/src/protocol/uc_global_time_sync_master.cpp
index 8f45c43c1a..8825c1ba85 100644
--- a/libuavcan/src/protocol/uc_global_time_sync_master.cpp
+++ b/libuavcan/src/protocol/uc_global_time_sync_master.cpp
@@ -56,11 +56,12 @@ int GlobalTimeSyncMaster::IfaceMaster::publish(TransferID tid, MonotonicTime cur
     const bool long_period = since_prev_pub.toMSec() >= protocol::GlobalTimeSync::MAX_PUBLICATION_PERIOD_MS;
 
     protocol::GlobalTimeSync msg;
-    msg.prev_utc_usec = long_period ? 0 : prev_tx_utc_.toUSec();
+    msg.previous_transmission_timestamp_usec = long_period ? 0 : prev_tx_utc_.toUSec();
     prev_tx_utc_ = UtcTime();
 
     UAVCAN_TRACE("GlobalTimeSyncMaster", "Publishing %llu iface=%i tid=%i",
-                 static_cast<unsigned long long>(msg.prev_utc_usec), int(iface_index_), int(tid.get()));
+                 static_cast<unsigned long long>(msg.previous_transmission_timestamp_usec),
+                 int(iface_index_), int(tid.get()));
     return pub_.broadcast(msg, tid);
 }
 
diff --git a/libuavcan/src/protocol/uc_global_time_sync_slave.cpp b/libuavcan/src/protocol/uc_global_time_sync_slave.cpp
index 67fe307efe..5a52ee29ae 100644
--- a/libuavcan/src/protocol/uc_global_time_sync_slave.cpp
+++ b/libuavcan/src/protocol/uc_global_time_sync_slave.cpp
@@ -11,8 +11,8 @@ namespace uavcan
 
 void GlobalTimeSyncSlave::adjustFromMsg(const ReceivedDataStructure<protocol::GlobalTimeSync>& msg)
 {
-    UAVCAN_ASSERT(msg.prev_utc_usec > 0);
-    const UtcDuration adjustment = UtcTime::fromUSec(msg.prev_utc_usec) - prev_ts_utc_;
+    UAVCAN_ASSERT(msg.previous_transmission_timestamp_usec > 0);
+    const UtcDuration adjustment = UtcTime::fromUSec(msg.previous_transmission_timestamp_usec) - prev_ts_utc_;
 
     UAVCAN_TRACE("GlobalTimeSyncSlave", "Adjustment: usec=%lli snid=%i iface=%i suppress=%i",
                  static_cast<long long>(adjustment.toUSec()),
@@ -58,7 +58,7 @@ void GlobalTimeSyncSlave::processMsg(const ReceivedDataStructure<protocol::Globa
     {
         if (state_ == Adjust)
         {
-            const bool msg_invalid = msg.prev_utc_usec == 0;
+            const bool msg_invalid = msg.previous_transmission_timestamp_usec == 0;
             const bool wrong_tid = prev_tid_.computeForwardDistance(msg.getTransferID()) != 1;
             const bool wrong_timing = since_prev_msg.toMSec() > protocol::GlobalTimeSync::MAX_PUBLICATION_PERIOD_MS;
             if (msg_invalid || wrong_tid || wrong_timing)
diff --git a/libuavcan/test/protocol/global_time_sync_slave.cpp b/libuavcan/test/protocol/global_time_sync_slave.cpp
index dbfde47502..5bb2e91c0d 100644
--- a/libuavcan/test/protocol/global_time_sync_slave.cpp
+++ b/libuavcan/test/protocol/global_time_sync_slave.cpp
@@ -37,9 +37,9 @@ TEST(GlobalTimeSyncSlave, Basic)
      * The slave must only register the timestamp and adjust nothing
      */
     uavcan::protocol::GlobalTimeSync gts;
-    gts.prev_utc_usec = 0;
+    gts.previous_transmission_timestamp_usec = 0;
     gts_pub.broadcast(gts);
-    gts.prev_utc_usec = master_clock.utc;
+    gts.previous_transmission_timestamp_usec = master_clock.utc;
     nodes.spinBoth(uavcan::MonotonicDuration::fromMSec(10));
     ASSERT_EQ(0, slave_clock.utc);
     ASSERT_EQ(1000000, master_clock.utc);
@@ -54,7 +54,7 @@ TEST(GlobalTimeSyncSlave, Basic)
      * Slave must adjust now
      */
     gts_pub.broadcast(gts);
-    gts.prev_utc_usec = master_clock.utc;
+    gts.previous_transmission_timestamp_usec = master_clock.utc;
     nodes.spinBoth(uavcan::MonotonicDuration());
     ASSERT_EQ(1000000, slave_clock.utc);
     ASSERT_EQ(1000000, master_clock.utc);
@@ -72,7 +72,7 @@ TEST(GlobalTimeSyncSlave, Basic)
      * Will update
      */
     gts_pub.broadcast(gts);
-    gts.prev_utc_usec = master_clock.utc;
+    gts.previous_transmission_timestamp_usec = master_clock.utc;
     nodes.spinBoth(uavcan::MonotonicDuration());
     ASSERT_EQ(2000000, slave_clock.utc);
     ASSERT_EQ(2000000, master_clock.utc);
@@ -88,7 +88,7 @@ TEST(GlobalTimeSyncSlave, Basic)
      * Will adjust
      */
     gts_pub.broadcast(gts);
-    gts.prev_utc_usec = master_clock.utc;
+    gts.previous_transmission_timestamp_usec = master_clock.utc;
     nodes.spinBoth(uavcan::MonotonicDuration());
     ASSERT_EQ(3000000, slave_clock.utc);
     ASSERT_EQ(3000000, master_clock.utc);
@@ -117,9 +117,9 @@ TEST(GlobalTimeSyncSlave, Basic)
     /*
      * Update step, no adjustment yet
      */
-    gts.prev_utc_usec = 0;
+    gts.previous_transmission_timestamp_usec = 0;
     gts_pub2.broadcast(gts);
-    gts.prev_utc_usec = master2_clock.utc;
+    gts.previous_transmission_timestamp_usec = master2_clock.utc;
     nodes.spinBoth(uavcan::MonotonicDuration());
     ASSERT_EQ(4000000, slave_clock.utc);
     ASSERT_EQ(100, master2_clock.utc);
@@ -142,7 +142,7 @@ TEST(GlobalTimeSyncSlave, Basic)
     /*
      * Another master will be ignored now
      */
-    gts.prev_utc_usec = 99999999;
+    gts.previous_transmission_timestamp_usec = 99999999;
     // Update
     gts_pub.broadcast(gts);
     nodes.spinBoth(uavcan::MonotonicDuration());