diff --git a/include/hardware/gps.h b/include/hardware/gps.h
index 76b6cb7..6fd47a9 100644
--- a/include/hardware/gps.h
+++ b/include/hardware/gps.h
@@ -53,7 +53,7 @@
 #define GPS_POSITION_MODE_MS_BASED      1
 /**
  * AGPS MS-Assisted mode. This mode is not maintained by the platform anymore.
- * It is strongly recommended to use GPS_POSITION_MODE_MS_BASE instead.
+ * It is strongly recommended to use GPS_POSITION_MODE_MS_BASED instead.
  */
 #define GPS_POSITION_MODE_MS_ASSISTED   2
 
@@ -98,28 +98,31 @@
 
 /** Flags for the gps_set_capabilities callback. */
 
-/** GPS HAL schedules fixes for GPS_POSITION_RECURRENCE_PERIODIC mode.
-    If this is not set, then the framework will use 1000ms for min_interval
-    and will start and call start() and stop() to schedule the GPS.
+/**
+ * GPS HAL schedules fixes for GPS_POSITION_RECURRENCE_PERIODIC mode. If this is
+ * not set, then the framework will use 1000ms for min_interval and will start
+ * and call start() and stop() to schedule the GPS.
  */
-#define GPS_CAPABILITY_SCHEDULING       0x0000001
+#define GPS_CAPABILITY_SCHEDULING       (1 << 0)
 /** GPS supports MS-Based AGPS mode */
-#define GPS_CAPABILITY_MSB              0x0000002
+#define GPS_CAPABILITY_MSB              (1 << 1)
 /** GPS supports MS-Assisted AGPS mode */
-#define GPS_CAPABILITY_MSA              0x0000004
+#define GPS_CAPABILITY_MSA              (1 << 2)
 /** GPS supports single-shot fixes */
-#define GPS_CAPABILITY_SINGLE_SHOT      0x0000008
+#define GPS_CAPABILITY_SINGLE_SHOT      (1 << 3)
 /** GPS supports on demand time injection */
-#define GPS_CAPABILITY_ON_DEMAND_TIME   0x0000010
+#define GPS_CAPABILITY_ON_DEMAND_TIME   (1 << 4)
 /** GPS supports Geofencing  */
-#define GPS_CAPABILITY_GEOFENCING       0x0000020
+#define GPS_CAPABILITY_GEOFENCING       (1 << 5)
 /** GPS supports Measurements */
-#define GPS_CAPABILITY_MEASUREMENTS     0x0000040
+#define GPS_CAPABILITY_MEASUREMENTS     (1 << 6)
 /** GPS supports Navigation Messages */
-#define GPS_CAPABILITY_NAV_MESSAGES     0x0000080
+#define GPS_CAPABILITY_NAV_MESSAGES     (1 << 7)
 
-/** Flags used to specify which aiding data to delete
-    when calling delete_aiding_data(). */
+/**
+ * Flags used to specify which aiding data to delete when calling
+ * delete_aiding_data().
+ */
 typedef uint16_t GpsAidingData;
 // IMPORTANT: Note that the following values must match
 // constants in GpsLocationProvider.java.
@@ -210,9 +213,11 @@
 /** AGPS data connection failed */
 #define GPS_AGPS_DATA_CONN_FAILED   5
 
+typedef uint16_t AGpsRefLocationType;
 #define AGPS_REF_LOCATION_TYPE_GSM_CELLID   1
 #define AGPS_REF_LOCATION_TYPE_UMTS_CELLID  2
 #define AGPS_REG_LOCATION_TYPE_MAC          3
+#define AGPS_REF_LOCATION_TYPE_LTE_CELLID   4
 
 /** Network types for update_network_state "type" parameter */
 #define AGPS_RIL_NETWORK_TYPE_MOBILE        0
@@ -246,9 +251,14 @@
  * Enumeration of the available values for the GPS Clock type.
  */
 typedef uint8_t GpsClockType;
-/** The type is not available ot it is unknown. */
+/** The type is not available or it is unknown. */
 #define GPS_CLOCK_TYPE_UNKNOWN                  0
-/** The source of the time value reported by GPS clock is the local hardware clock. */
+/**
+ * The source of the time value reported by GPS clock is the local hardware
+ * clock. This is a mandatory flag. When the GpsSystemInfo's year_of_hw is 2016
+ * or higher, it is mandatory that 'time' is populated with the local hardware
+ * clock value, and this flag must always be set.
+ */
 #define GPS_CLOCK_TYPE_LOCAL_HW_TIME            1
 /**
  * The source of the time value reported by GPS clock is the GPS time derived from satellites
@@ -296,7 +306,12 @@
 #define GPS_MEASUREMENT_HAS_DOPPLER_SHIFT_UNCERTAINTY         (1<<16)
 /** A valid 'used in fix' flag is stored in the data structure. */
 #define GPS_MEASUREMENT_HAS_USED_IN_FIX                       (1<<17)
-/** The value of 'pseudorange rate' is uncorrected. */
+/**
+ * The value of 'pseudorange rate' is uncorrected.
+ * This is a mandatory flag. It is mandatory that 'pseudorange rate' is
+ * populated with the uncorrected value, and this flag must always be set.
+ * See comments of GpsMeasurement::pseudorange_rate_mps for more details.
+ */
 #define GPS_MEASUREMENT_HAS_UNCORRECTED_PSEUDORANGE_RATE      (1<<18)
 
 /**
@@ -316,9 +331,9 @@
 typedef uint8_t GpsMultipathIndicator;
 /** The indicator is not available or unknown. */
 #define GPS_MULTIPATH_INDICATOR_UNKNOWN                 0
-/** The measurement has been indicated to use multipath. */
+/** The measurement is indicated to be affected by multipath. */
 #define GPS_MULTIPATH_INDICATOR_DETECTED                1
-/** The measurement has been indicated Not to use multipath. */
+/** The measurement is indicated to be not affected by multipath. */
 #define GPS_MULTIPATH_INDICATOR_NOT_USED                2
 
 /**
@@ -377,6 +392,27 @@
 #define NAV_MESSAGE_STATUS_PARITY_REBUILT  (1<<1)
 
 /**
+ * Flag that indicates which extra data GnssSvInfo includes.
+ */
+typedef uint8_t                                 GnssSvFlags;
+#define GNSS_SV_FLAGS_NONE                      0
+#define GNSS_SV_FLAGS_HAS_EPHEMERIS_DATA        (1 << 0)
+#define GNSS_SV_FLAGS_HAS_ALMANAC_DATA          (1 << 1)
+#define GNSS_SV_FLAGS_USED_IN_FIX               (1 << 2)
+
+/**
+ * Constellation type of GnssSvInfo
+ */
+typedef uint8_t                         GnssConstellationType;
+#define GNSS_CONSTELLATION_UNKNOWN      0
+#define GNSS_CONSTELLATION_GPS          1
+#define GNSS_CONSTELLATION_SBAS         2
+#define GNSS_CONSTELLATION_GLONASS      3
+#define GNSS_CONSTELLATION_QZSS         4
+#define GNSS_CONSTELLATION_BEIDOU       5
+#define GNSS_CONSTELLATION_GALILEO      6
+
+/**
  * Name for the GPS XTRA interface.
  */
 #define GPS_XTRA_INTERFACE      "gps-xtra"
@@ -437,8 +473,9 @@
     double          latitude;
     /** Represents longitude in degrees. */
     double          longitude;
-    /** Represents altitude in meters above the WGS 84 reference
-     * ellipsoid. */
+    /**
+     * Represents altitude in meters above the WGS 84 reference ellipsoid.
+     */
     double          altitude;
     /** Represents speed in meters per second. */
     float           speed;
@@ -471,43 +508,124 @@
     float   azimuth;
 } GpsSvInfo;
 
-/** Represents SV status. */
 typedef struct {
-    /** set to sizeof(GpsSvStatus) */
-    size_t          size;
-
-    /** Number of SVs currently visible. */
-    int         num_svs;
-
-    /** Contains an array of SV information. */
-    GpsSvInfo   sv_list[GPS_MAX_SVS];
-
-    /** Represents a bit mask indicating which SVs
-     * have ephemeris data.
-     */
-    uint32_t    ephemeris_mask;
-
-    /** Represents a bit mask indicating which SVs
-     * have almanac data.
-     */
-    uint32_t    almanac_mask;
+    /** set to sizeof(GnssSvInfo) */
+    size_t size;
 
     /**
-     * Represents a bit mask indicating which SVs
-     * were used for computing the most recent position fix.
+     * Pseudo-random number for the SV, or Amanac/slot number for Glonass. The
+     * distinction is made by looking at constellation field. Values should be
+     * in the range of:
+     *
+     * - GPS:     1-32
+     * - SBAS:    120-151, 183-192
+     * - GLONASS: 1-24 (slot number)
+     * - QZSS:    193-200
+     * - Galileo: 1-25
+     * - Beidou:  1-35
      */
-    uint32_t    used_in_fix_mask;
+    int prn;
+
+    /** Signal to noise ratio. */
+    float snr;
+
+    /** Elevation of SV in degrees. */
+    float elevation;
+
+    /** Azimuth of SV in degrees. */
+    float azimuth;
+
+    /**
+     * Contains additional data about the given SV. Value should be one of those
+     * GNSS_SV_FLAGS_* constants
+     */
+    GnssSvFlags flags;
+
+    /**
+     * Defines the constellation of the given SV. Value should be one of those
+     * GNSS_CONSTELLATION_* constants
+     */
+    GnssConstellationType constellation;
+
+} GnssSvInfo;
+
+/**
+ * Represents SV status.
+ *
+ * When switching from pre-N to N version of GpsSvStatus:
+ *
+ * 1) Fill in the fields from num_svs through used_in_fix_mask the same way as
+ * was done before, e.g. using the range of 65-88 to report Glonass info,
+ * 201-235 for Beidou, etc. (but with no used_in_fix_mask info - those are
+ * index by prn, and thus for GPS only). This will help ensure compatibility
+ * when a newer GPS HAL is used with an older version of Android.
+ *
+ * 2) Fill in the gnss_sv_list with information about SVs from all
+ * constellations (GPS & other GNSS's) - when this is filled in, this will be
+ * the only source of information about satellite status (e.g. for working with
+ * GpsStatus facing applications), the earlier fields will be ignored.
+ */
+typedef struct {
+    /** set to sizeof(GpsSvStatus) */
+    size_t size;
+
+    /** Number of GPS SVs currently visible, refers to the SVs stored in sv_list */
+    int num_svs;
+
+    /** Contains an array of GPS SV information in legacy GPS format. */
+    GpsSvInfo sv_list[GPS_MAX_SVS];
+
+    /**
+     * Represents a bit mask indicating which GPS SVs have ephemeris data,
+     * refers to sv_list.
+     */
+    uint32_t ephemeris_mask;
+
+    /**
+     * Represents a bit mask indicating which GPS SVs have almanac data, refers
+     * to sv_list.
+     */
+    uint32_t almanac_mask;
+
+    /**
+     * Represents a bit mask indicating which GPS SVs
+     * were used for computing the most recent position fix,
+     * refers to sv_list.
+     */
+    uint32_t used_in_fix_mask;
+
+    /**
+     * Size of the array which contains SV info for all GNSS constellation
+     * except for GPS.
+     */
+    size_t gnss_sv_list_size;
+
+    /**
+     * Pointer to an array of SVs information for all GNSS constellations,
+     * except GPS, which is reported using sv_list
+     */
+    GnssSvInfo* gnss_sv_list;
+
 } GpsSvStatus;
 
-
-/* 2G and 3G */
-/* In 3G lac is discarded */
+/* CellID for 2G, 3G and LTE, used in AGPS. */
 typedef struct {
-    uint16_t type;
+    AGpsRefLocationType type;
+    /** Mobile Country Code. */
     uint16_t mcc;
+    /** Mobile Network Code .*/
     uint16_t mnc;
+    /** Location Area Code in 2G, 3G and LTE. In 3G lac is discarded. In LTE,
+     * lac is populated with tac, to ensure that we don't break old clients that
+     * might rely in the old (wrong) behavior.
+     */
     uint16_t lac;
+    /** Cell id in 2G. Utran Cell id in 3G. Cell Global Id EUTRA in LTE. */
     uint32_t cid;
+    /** Tracking Area Code in LTE. */
+    uint16_t tac;
+    /** Physical Cell id in LTE (not used in 2G and 3G) */
+    uint16_t pcid;
 } AGpsRefLocationCellID;
 
 typedef struct {
@@ -516,20 +634,22 @@
 
 /** Represents ref locations */
 typedef struct {
-    uint16_t type;
+    AGpsRefLocationType type;
     union {
         AGpsRefLocationCellID   cellID;
         AGpsRefLocationMac      mac;
     } u;
 } AGpsRefLocation;
 
-/** Callback with location information.
- *  Can only be called from a thread created by create_thread_cb.
+/**
+ * Callback with location information. Can only be called from a thread created
+ * by create_thread_cb.
  */
 typedef void (* gps_location_callback)(GpsLocation* location);
 
-/** Callback with status information.
- *  Can only be called from a thread created by create_thread_cb.
+/**
+ * Callback with status information. Can only be called from a thread created by
+ * create_thread_cb.
  */
 typedef void (* gps_status_callback)(GpsStatus* status);
 
@@ -539,18 +659,21 @@
  */
 typedef void (* gps_sv_status_callback)(GpsSvStatus* sv_info);
 
-/** Callback for reporting NMEA sentences.
- *  Can only be called from a thread created by create_thread_cb.
+/**
+ * Callback for reporting NMEA sentences. Can only be called from a thread
+ * created by create_thread_cb.
  */
 typedef void (* gps_nmea_callback)(GpsUtcTime timestamp, const char* nmea, int length);
 
-/** Callback to inform framework of the GPS engine's capabilities.
- *  Capability parameter is a bit field of GPS_CAPABILITY_* flags.
+/**
+ * Callback to inform framework of the GPS engine's capabilities. Capability
+ * parameter is a bit field of GPS_CAPABILITY_* flags.
  */
 typedef void (* gps_set_capabilities)(uint32_t capabilities);
 
-/** Callback utility for acquiring the GPS wakelock.
- *  This can be used to prevent the CPU from suspending while handling GPS events.
+/**
+ * Callback utility for acquiring the GPS wakelock. This can be used to prevent
+ * the CPU from suspending while handling GPS events.
  */
 typedef void (* gps_acquire_wakelock)();
 
@@ -560,12 +683,57 @@
 /** Callback for requesting NTP time */
 typedef void (* gps_request_utc_time)();
 
-/** Callback for creating a thread that can call into the Java framework code.
- *  This must be used to create any threads that report events up to the framework.
+/**
+ * Callback for creating a thread that can call into the Java framework code.
+ * This must be used to create any threads that report events up to the
+ * framework.
  */
 typedef pthread_t (* gps_create_thread)(const char* name, void (*start)(void *), void* arg);
 
-/** GPS callback structure. */
+/**
+ * Provides information about how new the underlying GPS/GNSS hardware and
+ * software is.
+ *
+ * This information will be available for Android Test Applications. If a GPS
+ * HAL does not provide this information, it will be considered "2015 or
+ * earlier".
+ *
+ * If a GPS HAL does provide this information, then newer years will need to
+ * meet newer CTS standards. E.g. if the date are 2016 or above, then N+ level
+ * GpsMeasurement support will be verified.
+ */
+typedef struct {
+    /** Set to sizeof(GpsSystemInfo) */
+    size_t   size;
+    /* year in which the last update was made to the underlying hardware/firmware
+     * used to capture GNSS signals, e.g. 2016 */
+    uint16_t year_of_hw;
+} GpsSystemInfo;
+
+/**
+ * Callback to inform framework of the engine's hardware version information.
+ */
+typedef void (*gps_set_system_info)(const GpsSystemInfo* info);
+
+/**
+ * Legacy GPS callback structure.
+ * See GpsCallbacks for more information.
+ */
+typedef struct {
+    /** set to sizeof(GpsCallbacks_v1) */
+    size_t      size;
+    gps_location_callback location_cb;
+    gps_status_callback status_cb;
+    gps_sv_status_callback sv_status_cb;
+    gps_nmea_callback nmea_cb;
+    gps_set_capabilities set_capabilities_cb;
+    gps_acquire_wakelock acquire_wakelock_cb;
+    gps_release_wakelock release_wakelock_cb;
+    gps_create_thread create_thread_cb;
+    gps_request_utc_time request_utc_time_cb;
+} GpsCallbacks_v1;
+
+/** New GPS callback structure. */
 typedef struct {
     /** set to sizeof(GpsCallbacks) */
     size_t      size;
@@ -578,8 +746,17 @@
     gps_release_wakelock release_wakelock_cb;
     gps_create_thread create_thread_cb;
     gps_request_utc_time request_utc_time_cb;
-} GpsCallbacks;
 
+    /**
+     * Callback for the chipset to report system information.
+     *
+     * This field is newly introduced since N. The driver implementation must
+     * check 'size' field against 'sizeof(GpsCallbacks)' and
+     * 'sizeof(GpsCallbacks_v1)' to decide whether the new field is valid before
+     * calling it.
+     */
+    gps_set_system_info set_system_info_cb;
+} GpsCallbacks;
 
 /** Represents the standard GPS interface. */
 typedef struct {
@@ -604,10 +781,10 @@
     int   (*inject_time)(GpsUtcTime time, int64_t timeReference,
                          int uncertainty);
 
-    /** Injects current location from another location provider
-     *  (typically cell ID).
-     *  latitude and longitude are measured in degrees
-     *  expected accuracy is measured in meters
+    /**
+     * Injects current location from another location provider (typically cell
+     * ID). Latitude and longitude are measured in degrees expected accuracy is
+     * measured in meters
      */
     int  (*inject_location)(double latitude, double longitude, float accuracy);
 
@@ -623,10 +800,10 @@
      * preferred_accuracy represents the requested fix accuracy in meters.
      * preferred_time represents the requested time to first fix in milliseconds.
      *
-     * 'mode' parameter should be one of GPS_POSITION_MODE_MS_BASE
+     * 'mode' parameter should be one of GPS_POSITION_MODE_MS_BASED
      * or GPS_POSITION_MODE_STANDALONE.
      * It is allowed by the platform (and it is recommended) to fallback to
-     * GPS_POSITION_MODE_MS_BASE if GPS_POSITION_MODE_MS_ASSISTED is passed in, and
+     * GPS_POSITION_MODE_MS_BASED if GPS_POSITION_MODE_MS_ASSISTED is passed in, and
      * GPS_POSITION_MODE_MS_BASED is supported.
      */
     int   (*set_position_mode)(GpsPositionMode mode, GpsPositionRecurrence recurrence,
@@ -636,9 +813,10 @@
     const void* (*get_extension)(const char* name);
 } GpsInterface;
 
-/** Callback to request the client to download XTRA data.
- *  The client should download XTRA data and inject it by calling inject_xtra_data().
- *  Can only be called from a thread created by create_thread_cb.
+/**
+ * Callback to request the client to download XTRA data. The client should
+ * download XTRA data and inject it by calling inject_xtra_data(). Can only be
+ * called from a thread created by create_thread_cb.
  */
 typedef void (* gps_xtra_download_request)();
 
@@ -673,36 +851,11 @@
     size_t (*get_internal_state)(char* buffer, size_t bufferSize);
 } GpsDebugInterface;
 
-#pragma pack(push,4)
-// We need to keep the alignment of this data structure to 4-bytes, to ensure that in 64-bit
-// environments the size of this legacy definition does not collide with _v2. Implementations should
-// be using _v2 and _v3, so it's OK to pay the 'unaligned' penalty in 64-bit if an old
-// implementation is still in use.
-
-/** Represents the status of AGPS. */
+/*
+ * Represents the status of AGPS augmented to support IPv4 and IPv6.
+ */
 typedef struct {
-    /** set to sizeof(AGpsStatus_v1) */
-    size_t          size;
-
-    AGpsType        type;
-    AGpsStatusValue status;
-} AGpsStatus_v1;
-
-#pragma pack(pop)
-
-/** Represents the status of AGPS augmented with a IPv4 address field. */
-typedef struct {
-    /** set to sizeof(AGpsStatus_v2) */
-    size_t          size;
-
-    AGpsType        type;
-    AGpsStatusValue status;
-    uint32_t        ipaddr;
-} AGpsStatus_v2;
-
-/* Represents the status of AGPS augmented to support IPv4 and IPv6. */
-typedef struct {
-    /** set to sizeof(AGpsStatus_v3) */
+    /** set to sizeof(AGpsStatus) */
     size_t                  size;
 
     AGpsType                type;
@@ -717,14 +870,13 @@
     /**
      * Must contain the IPv4 (AF_INET) or IPv6 (AF_INET6) address to report.
      * Any other value of addr.ss_family will be rejected.
-     * */
+     */
     struct sockaddr_storage addr;
-} AGpsStatus_v3;
+} AGpsStatus;
 
-typedef AGpsStatus_v3     AGpsStatus;
-
-/** Callback with AGPS status information.
- *  Can only be called from a thread created by create_thread_cb.
+/**
+ * Callback with AGPS status information. Can only be called from a thread
+ * created by create_thread_cb.
  */
 typedef void (* agps_status_callback)(AGpsStatus* status);
 
@@ -734,42 +886,12 @@
     gps_create_thread create_thread_cb;
 } AGpsCallbacks;
 
-
-/** Extended interface for AGPS support. */
-typedef struct {
-    /** set to sizeof(AGpsInterface_v1) */
-    size_t          size;
-
-    /**
-     * Opens the AGPS interface and provides the callback routines
-     * to the implementation of this interface.
-     */
-    void  (*init)( AGpsCallbacks* callbacks );
-    /**
-     * Notifies that a data connection is available and sets
-     * the name of the APN to be used for SUPL.
-     */
-    int  (*data_conn_open)( const char* apn );
-    /**
-     * Notifies that the AGPS data connection has been closed.
-     */
-    int  (*data_conn_closed)();
-    /**
-     * Notifies that a data connection is not available for AGPS.
-     */
-    int  (*data_conn_failed)();
-    /**
-     * Sets the hostname and port for the AGPS server.
-     */
-    int  (*set_server)( AGpsType type, const char* hostname, int port );
-} AGpsInterface_v1;
-
 /**
  * Extended interface for AGPS support, it is augmented to enable to pass
  * extra APN data.
  */
 typedef struct {
-    /** set to sizeof(AGpsInterface_v2) */
+    /** set to sizeof(AGpsInterface) */
     size_t size;
 
     /**
@@ -803,9 +925,7 @@
     int (*data_conn_open_with_apn_ip_type)(
             const char* apn,
             ApnIpType apnIpType);
-} AGpsInterface_v2;
-
-typedef AGpsInterface_v2    AGpsInterface;
+} AGpsInterface;
 
 /** Error codes associated with certificate operations */
 #define AGPS_CERTIFICATE_OPERATION_SUCCESS               0
@@ -936,8 +1056,9 @@
 
 } GpsNiNotification;
 
-/** Callback with NI notification.
- *  Can only be called from a thread created by create_thread_cb.
+/**
+ * Callback with NI notification. Can only be called from a thread created by
+ * create_thread_cb.
  */
 typedef void (*gps_ni_notify_callback)(GpsNiNotification *notification);
 
@@ -1280,7 +1401,6 @@
    void (*remove_geofence_area) (int32_t geofence_id);
 } GpsGeofencingInterface;
 
-
 /**
  * Represents an estimate of the GPS clock time.
  */
@@ -1302,7 +1422,7 @@
 
     /**
      * Indicates the type of time reported by the 'time_ns' field.
-     * This is a Mandatory field.
+     * This is a mandatory field.
      */
     GpsClockType type;
 
@@ -1321,7 +1441,11 @@
      * Sub-nanosecond accuracy can be provided by means of the 'bias' field.
      * The value contains the 'time uncertainty' in it.
      *
-     * This is a Mandatory field.
+     * This field is mandatory.
+     *
+     * For devices where GpsSystemInfo's year_of_hw is set to 2016+, it is
+     * mandatory that it contains the value from the 'local hardware clock, and
+     * thus GPS_CLOCK_TYPE_LOCAL_HW_TIME must be set in 'type' field.
      */
     int64_t time_ns;
 
@@ -1329,8 +1453,9 @@
      * 1-Sigma uncertainty associated with the clock's time in nanoseconds.
      * The uncertainty is represented as an absolute (single sided) value.
      *
-     * This value should be set if GPS_CLOCK_TYPE_GPS_TIME is set.
-     * If the data is available 'flags' must contain GPS_CLOCK_HAS_TIME_UNCERTAINTY.
+     * If the data is available, 'flags' must contain
+     * GPS_CLOCK_HAS_TIME_UNCERTAINTY. If GPS has computed a position fix, this
+     * field is mandatory and must be populated.
      */
     double time_uncertainty_ns;
 
@@ -1345,8 +1470,9 @@
      *      true time (GPS time) = time_ns + (full_bias_ns + bias_ns)
      *
      * This value contains the 'bias uncertainty' in it.
-     * If the data is available 'flags' must contain GPS_CLOCK_HAS_FULL_BIAS.
-
+     * If GPS has computed a position fix this field is mandatory and must be
+     * populated. If the data is available 'flags' must contain
+     * GPS_CLOCK_HAS_FULL_BIAS.
      */
     int64_t full_bias_ns;
 
@@ -1354,7 +1480,9 @@
      * Sub-nanosecond bias.
      * The value contains the 'bias uncertainty' in it.
      *
-     * If the data is available 'flags' must contain GPS_CLOCK_HAS_BIAS.
+     * If the data is available 'flags' must contain GPS_CLOCK_HAS_BIAS. If GPS
+     * has computed a position fix, this field is mandatory and must be
+     * populated.
      */
     double bias_ns;
 
@@ -1362,7 +1490,9 @@
      * 1-Sigma uncertainty associated with the clock's bias in nanoseconds.
      * The uncertainty is represented as an absolute (single sided) value.
      *
-     * If the data is available 'flags' must contain GPS_CLOCK_HAS_BIAS_UNCERTAINTY.
+     * If the data is available 'flags' must contain
+     * GPS_CLOCK_HAS_BIAS_UNCERTAINTY. If GPS has computed a position fix this
+     * field is mandatory and must be populated.
      */
     double bias_uncertainty_ns;
 
@@ -1373,8 +1503,10 @@
      * The value contains the 'drift uncertainty' in it.
      * If the data is available 'flags' must contain GPS_CLOCK_HAS_DRIFT.
      *
-     * If GpsMeasurement's 'flags' field contains GPS_MEASUREMENT_HAS_UNCORRECTED_PSEUDORANGE_RATE,
-     * it is encouraged that this field is also provided.
+     * If GpsMeasurement's 'flags' field contains
+     * GPS_MEASUREMENT_HAS_UNCORRECTED_PSEUDORANGE_RATE, it is encouraged that
+     * this field is also provided. If GPS has computed a position fix this
+     * field is mandatory and must be populated.
      */
     double drift_nsps;
 
@@ -1382,9 +1514,30 @@
      * 1-Sigma uncertainty associated with the clock's drift in nanoseconds (per second).
      * The uncertainty is represented as an absolute (single sided) value.
      *
-     * If the data is available 'flags' must contain GPS_CLOCK_HAS_DRIFT_UNCERTAINTY.
+     * If the data is available 'flags' must contain
+     * GPS_CLOCK_HAS_DRIFT_UNCERTAINTY. If GPS has computed a position fix this
+     * field is mandatory and must be populated.
      */
     double drift_uncertainty_nsps;
+
+    /**
+     * When the GPS_CLOCK_TYPE_LOCAL_HW_TIME is set, this field is mandatory.
+     *
+     * A "discontinuity" is meant to cover the case of a switch from one source
+     * of clock to another.  A single free-running crystal oscillator (XO)
+     * should generally not have any discontinuities, and this can be set to 0.
+     * If, however, the time_ns value (HW clock) is derived from a composite of
+     * sources, that is not as smooth as a typical XO, then this value shall be
+     * set to the time_ns value since which the time_ns has been derived from a
+     * single, high quality clock (XO like, or better, that's typically used
+     * during continuous GPS signal sampling.)
+     *
+     * It is expected, esp. during periods where there are few GNSS signals
+     * available, that the HW clock be discontinuity-free as long as possible,
+     * as this avoids the need to use (waste) a GPS measurement to fully
+     * re-solve for the clock bias and drift.
+     */
+    int64_t time_of_last_hw_clock_discontinuity_ns;
 } GpsClock;
 
 /**
@@ -1399,7 +1552,7 @@
 
     /**
      * Pseudo-random number in the range of [1, 32]
-     * This is a Mandatory value.
+     * This is a mandatory value.
      */
     int8_t prn;
 
@@ -1412,7 +1565,7 @@
      *      measurement time = GpsClock::time_ns + time_offset_ns
      *
      * It provides an individual time-stamp for the measurement, and allows sub-nanosecond accuracy.
-     * This is a Mandatory value.
+     * This is a mandatory value.
      */
     double time_offset_ns;
 
@@ -1420,7 +1573,7 @@
      * Per satellite sync state. It represents the current sync state for the associated satellite.
      * Based on the sync state, the 'received GPS tow' field should be interpreted accordingly.
      *
-     * This is a Mandatory value.
+     * This is a mandatory value.
      */
     GpsMeasurementState state;
 
@@ -1454,7 +1607,7 @@
      * Carrier-to-noise density in dB-Hz, in the range [0, 63].
      * It contains the measured C/N0 value for the signal at the antenna input.
      *
-     * This is a Mandatory value.
+     * This is a mandatory value.
      */
     double c_n0_dbhz;
 
@@ -1463,13 +1616,9 @@
      * The correction of a given Pseudorange Rate value includes corrections for receiver and
      * satellite clock frequency errors.
      *
-     * If GPS_MEASUREMENT_HAS_UNCORRECTED_PSEUDORANGE_RATE is set in 'flags' field, this field must
-     * be populated with the 'uncorrected' reading.
-     * If GPS_MEASUREMENT_HAS_UNCORRECTED_PSEUDORANGE_RATE is not set in 'flags' field, this field
-     * must be populated with the 'corrected' reading. This is the default behavior.
-     *
      * It is encouraged to provide the 'uncorrected' 'pseudorange rate', and provide GpsClock's
-     * 'drift' field as well.
+     * 'drift' field as well. When providing the uncorrected pseudorange rate,
+     * do not apply the corrections described above.
      *
      * The value includes the 'pseudorange rate uncertainty' in it.
      * A positive 'uncorrected' value indicates that the SV is moving away from the receiver.
@@ -1478,15 +1627,22 @@
      * shift' is given by the equation:
      *      pseudorange rate = -k * doppler shift   (where k is a constant)
      *
-     * This is a Mandatory value.
+     * This field should be based on the signal energy doppler measurement. (See
+     * also pseudorate_rate_carrier_mps for a similar field, based on carrier
+     * phase changes.)
+     *
+     * This is a mandatory value. It is mandatory (and expected) that it
+     * contains the 'uncorrected' reading, and
+     * GPS_MEASUREMENT_HAS_UNCORRECTED_PSEUDORANGE_RATE must be set in 'flags'
+     * field.
      */
     double pseudorange_rate_mps;
 
     /**
-     * 1-Sigma uncertainty of the pseudurange rate in m/s.
+     * 1-Sigma uncertainty of the pseudorange_rate_mps.
      * The uncertainty is represented as an absolute (single sided) value.
      *
-     * This is a Mandatory value.
+     * This is a mandatory value.
      */
     double pseudorange_rate_uncertainty_mps;
 
@@ -1494,7 +1650,7 @@
      * Accumulated delta range's state. It indicates whether ADR is reset or there is a cycle slip
      * (indicating loss of lock).
      *
-     * This is a Mandatory value.
+     * This is a mandatory value.
      */
     GpsAccumulatedDeltaRangeState accumulated_delta_range_state;
 
@@ -1651,7 +1807,7 @@
      * Azimuth in degrees, in the range [0, 360).
      * The value contains the 'azimuth uncertainty' in it.
      * If the data is available, 'flags' must contain GPS_MEASUREMENT_HAS_AZIMUTH.
-     *  */
+     */
     double azimuth_deg;
 
     /**
@@ -1667,6 +1823,41 @@
      * If the data is available, 'flags' must contain GPS_MEASUREMENT_HAS_USED_IN_FIX.
      */
     bool used_in_fix;
+
+    /**
+     * Pseudorange rate (based on carrier phase changes) at the timestamp in m/s.
+     *
+     * The correction of a given Pseudorange Rate value includes corrections for
+     * receiver and satellite clock frequency errors.
+     *
+     * It is mandatory to provide the 'uncorrected' 'pseudorange rate' in this
+     * field. (Do not apply the corrections described above.)
+     *
+     * The value includes the 'pseudorange rate (carrier) uncertainty' in it. A
+     * positive 'uncorrected' value indicates that the SV is moving away from
+     * the receiver.
+     *
+     * The sign of the 'uncorrected' 'pseudorange rate' and its relation to the
+     * sign of 'doppler shift' is given by the equation:
+     *
+     *      pseudorange rate = -k * doppler shift   (where k is a constant)
+     *
+     * This field must be based on changes in the carrier phase measurement.
+     * (See pseudorange_rate_mps for a similar field, based on signal energy
+     * doppler.)
+     *
+     * It is mandatory that this value be provided, when signals are
+     * sufficiently strong, e.g. signals from a GPS simulator at >= 30 dB-Hz.
+     */
+    double pseudorange_rate_carrier_mps;
+    /**
+     * 1-Sigma uncertainty of the pseudorange_rate_carrier_mps.
+     * The uncertainty is represented as an absolute (single sided) value.
+     *
+     * This is a mandatory value when pseudorange_rate_carrier_mps is provided.
+     */
+    double pseudorange_rate_carrier_uncertainty_mps;
+
 } GpsMeasurement;
 
 /** Represents a reading of GPS measurements. */
@@ -1740,13 +1931,13 @@
 
     /**
      * Pseudo-random number in the range of [1, 32]
-     * This is a Mandatory value.
+     * This is a mandatory value.
      */
     int8_t prn;
 
     /**
      * The type of message contained in the structure.
-     * This is a Mandatory value.
+     * This is a mandatory value.
      */
     GpsNavigationMessageType type;
 
@@ -1778,7 +1969,7 @@
      * If this value is different from zero, 'data' must point to an array of the same size.
      * e.g. for L1 C/A the size of the sub-frame will be 40 bytes (10 words, 30 bits/word).
      *
-     * This is a Mandatory value.
+     * This is a mandatory value.
      */
     size_t data_length;