diff --git a/Adafruit_GPS.h b/Adafruit_GPS.h
index b3d63b8..a417255 100755
--- a/Adafruit_GPS.h
+++ b/Adafruit_GPS.h
@@ -32,12 +32,12 @@ All text above must be included in any redistribution
 // different commands to set the update rate from once a second (1 Hz) to 10 times a second (10Hz)
 // Note that these only control the rate at which the position is echoed, to actually speed up the
 // position fix you must also send one of the position fix rate commands below too.
-#define PMTK_SET_NMEA_UPDATE_10HZ  "$PMTK220,10000*2F"
+#define PMTK_SET_NMEA_UPDATE_100_MILLIHERTZ  "$PMTK220,10000*2F" // Once every 10 seconds, 100 millihertz.
 #define PMTK_SET_NMEA_UPDATE_1HZ  "$PMTK220,1000*1F"
 #define PMTK_SET_NMEA_UPDATE_5HZ  "$PMTK220,200*2C"
 #define PMTK_SET_NMEA_UPDATE_10HZ "$PMTK220,100*2F"
 // Position fix update rate commands.
-#define PMTK_API_SET_FIX_CTL_10HZ  "$PMTK300,10000,0,0,0,0*2C"
+#define PMTK_API_SET_FIX_CTL_100_MILLIHERTZ  "$PMTK300,10000,0,0,0,0*2C" // Once every 10 seconds, 100 millihertz.
 #define PMTK_API_SET_FIX_CTL_1HZ  "$PMTK300,1000,0,0,0,0*1C"
 #define PMTK_API_SET_FIX_CTL_5HZ  "$PMTK300,200,0,0,0,0*2F"
 // Can't fix position faster than 5 times a second!