gitphp 0.2.9.1 :: busui.git/blobdiff

//

// The content of this file is licensed under the Creative Commons Attribution

// 3.0 License.

//

// Protocol definition file for GTFS-realtime.

//

// GTFS-realtime lets transit agencies provide consumers with realtime

// information about disruptions to their service (stations closed, lines not

// operating, important delays etc), location of their vehicles and expected

// arrival times.

//

// This protocol is published on http://code.google.com/transit/realtime/ .

syntax = "proto2";

option cc_api_version = 2;

option py_api_version = 1;

option java_package = "com.google.transit.realtime";

package transit_realtime;

// The contents of a feed message.

// A feed is a continuous stream of feed messages. Each message in the stream is

// obtained as a response to an appropriate HTTP GET request.

// A realtime feed is always defined with relation to an existing GTFS feed.

// All the entity ids are resolved with respect to the GTFS feed.

//

// A feed depends on some external configuration:

// - The corresponding GTFS feed.

// - Feed application (updates, positions or alerts). A feed should contain only

// items of one specified application; all the other entities will be ignored.

// - Polling frequency

message FeedMessage {

// Metadata about this feed and feed message.

required FeedHeader header = 1;

// Contents of the feed.

repeated FeedEntity entity = 2;

}

// Metadata about a feed, included in feed messages.

message FeedHeader {

// Version of the feed specification.

// The current version is 1.0.

required string gtfs_realtime_version = 1;

// Determines whether the current fetch is incremental.

enum Incrementality {

FULL_DATASET = 0;

DIFFERENTIAL = 1;

}

optional Incrementality incrementality = 2 [default = FULL_DATASET];

// This timestamp identifies the moment when the content of this feed has been

// created (in server time). In POSIX time (i.e., number of seconds since

// January 1st 1970 00:00:00 UTC).

optional uint64 timestamp = 3;

}

// A definition (or update) of an entity in the transit feed.

message FeedEntity {

// The ids are used only to provide incrementality support. The id should be

// unique within a FeedMessage. Consequent FeedMessages may contain

// FeedEntities with the same id. In case of a DIFFERENTIAL update the new

// FeedEntity with some id will replace the old FeedEntity with the same id

// (or delete it - see is_deleted below).

// The actual GTFS entities (e.g. stations, routes, trips) referenced by the

// feed must be specified by explicit selectors (see EntitySelector below for

// more info).

required string id = 1;

// Whether this entity is to be deleted. Relevant only for incremental

// fetches.

optional bool is_deleted = 2 [default = false];

// Data about the entity itself. Exactly one of the following fields must be

// present (unless the entity is being deleted).

optional TripUpdate trip_update = 3;

optional VehiclePosition vehicle = 4;

optional Alert alert = 5;

}

//

// Entities used in the feed.

//

// Realtime update of the progress of a vehicle along a trip.

// Depending on the value of ScheduleRelationship, a TripUpdate can specify:

// - A trip that proceeds along the schedule.

// - A trip that proceeds along a route but has no fixed schedule.

// - A trip that have been added or removed with regard to schedule.

//

// The updates can be for future, predicted arrival/departure events, or for

// past events that already occurred.

// Normally, updates should get more precise and more certain (see

// uncertainty below) as the events gets closer to current time.

// Even if that is not possible, the information for past events should be

// precise and certain. In particular, if an update points to time in the past

// but its update's uncertainty is not 0, the client should conclude that the

// update is a (wrong) prediction and that the trip has not completed yet.

//

// Note that the update can describe a trip that is already completed.

// To this end, it is enough to provide an update for the last stop of the trip.

// If the time of that is in the past, the client will conclude from that that

// the whole trip is in the past (it is possible, although inconsequential, to

// also provide updates for preceding stops).

// This option is most relevant for a trip that has completed ahead of schedule,

// but according to the schedule, the trip is still proceeding at the current

// time. Removing the updates for this trip could make the client assume

// that the trip is still proceeding.

// Note that the feed provider is allowed, but not required, to purge past

// updates - this is one case where this would be practically useful.

message TripUpdate {

// The Trip that this message applies to. There can be at most one

// TripUpdate entity for each actual trip instance.

// If there is none, that means there is no prediction information available.

// It does *not* mean that the trip is progressing according to schedule.

required TripDescriptor trip = 1;

// Additional information on the vehicle that is serving this trip.

optional VehicleDescriptor vehicle = 3;

// Timing information for a single predicted event (either arrival or

// departure).

// Timing consists of delay and/or estimated time, and uncertainty.

// - delay should be used when the prediction is given relative to some

// existing schedule in GTFS.

// - time should be given whether there is a predicted schedule or not. If

// both time and delay are specified, time will take precedence

// (although normally, time, if given for a scheduled trip, should be

// equal to scheduled time in GTFS + delay).

//

// Uncertainty applies equally to both time and delay.

// The uncertainty roughly specifies the expected error in true delay (but

// note, we don't yet define its precise statistical meaning). It's possible

// for the uncertainty to be 0, for example for trains that are driven under

// computer timing control.

message StopTimeEvent {

// Delay (in seconds) can be positive (meaning that the vehicle is late) or

// negative (meaning that the vehicle is ahead of schedule). Delay of 0

// means that the vehicle is exactly on time.

optional int32 delay = 1;

// Event as absolute time.

// In Unix time (i.e., number of seconds since January 1st 1970 00:00:00

// UTC).

optional int64 time = 2;

// If uncertainty is omitted, it is interpreted as unknown.

// If the prediction is unknown or too uncertain, the delay (or time) field

// should be empty. In such case, the uncertainty field is ignored.

// To specify a completely certain prediction, set its uncertainty to 0.

optional int32 uncertainty = 3;

}

// Realtime update for arrival and/or departure events for a given stop on a

// trip. Updates can be supplied for both past and future events.

// The producer is allowed, although not required, to drop past events.

message StopTimeUpdate {

// The update is linked to a specific stop either through stop_sequence or

// stop_id, so one of the fields below must necessarily be set.

// See the documentation in TripDescriptor for more information.

// Must be the same as in stop_times.txt in the corresponding GTFS feed.

optional uint32 stop_sequence = 1;

// Must be the same as in stops.txt in the corresponding GTFS feed.

optional string stop_id = 4;

optional StopTimeEvent arrival = 2;

optional StopTimeEvent departure = 3;

// The relation between this StopTime and the static schedule.

enum ScheduleRelationship {

// The vehicle is proceeding in accordance with its static schedule of

// stops, although not necessarily according to the times of the schedule.

// At least one of arrival and departure must be provided. If the schedule

// for this stop contains both arrival and departure times then so must

// this update. An update with only an arrival, say, where the schedule

// has both, indicates that the trip is terminating early at this stop.

SCHEDULED = 0;

// The stop is skipped, i.e., the vehicle will not stop at this stop.

// Arrival and departure are optional.

SKIPPED = 1;

// No data is given for this stop. The main intention for this value is to

// give the predictions only for part of a trip, i.e., if the last update

// for a trip has a NO_DATA specifier, then StopTimes for the rest of the

// stops in the trip are considered to be unspecified as well.

// Neither arrival nor departure should be supplied.

NO_DATA = 2;

}

optional ScheduleRelationship schedule_relationship = 5

[default = SCHEDULED];

}

// Updates to StopTimes for the trip (both future, i.e., predictions, and in

// some cases, past ones, i.e., those that already happened).

// The updates must be sorted by stop_sequence, and apply for all the

// following stops of the trip up to the next specified one.

//

// Example 1:

// For a trip with 20 stops, a StopTimeUpdate with arrival delay and departure

// delay of 0 for stop_sequence of the current stop means that the trip is

// exactly on time.

//

// Example 2:

// For the same trip instance, 3 StopTimeUpdates are provided:

// - delay of 5 min for stop_sequence 3

// - delay of 1 min for stop_sequence 8

// - delay of unspecified duration for stop_sequence 10

// This will be interpreted as:

// - stop_sequences 3,4,5,6,7 have delay of 5 min.

// - stop_sequences 8,9 have delay of 1 min.

// - stop_sequences 10,... have unknown delay.

repeated StopTimeUpdate stop_time_update = 2;

}

// Realtime positioning information for a given vehicle.

message VehiclePosition {

// The Trip that this vehicle is serving.

// Can be empty or partial if the vehicle can not be identified with a given

// trip instance.

optional TripDescriptor trip = 1;

// Additional information on the vehicle that is serving this trip.

optional VehicleDescriptor vehicle = 8;

// Current position of this vehicle.

optional Position position = 2;

// The stop sequence index of the current stop. The meaning of

// current_stop_sequence (i.e., the stop that it refers to) is determined by

// current_status.

// If current_status is missing IN_TRANSIT_TO is assumed.

optional uint32 current_stop_sequence = 3;

// Identifies the current stop. The value must be the same as in stops.txt in

// the corresponding GTFS feed.

optional string stop_id = 7;

enum VehicleStopStatus {

// The vehicle is just about to arrive at the stop (on a stop

// display, the vehicle symbol typically flashes).

INCOMING_AT = 0;

// The vehicle is standing at the stop.

STOPPED_AT = 1;

// The vehicle has departed and is in transit to the next stop.

IN_TRANSIT_TO = 2;

}

// The exact status of the vehicle with respect to the current stop.

// Ignored if current_stop_sequence is missing.

optional VehicleStopStatus current_status = 4 [default = IN_TRANSIT_TO];

// Moment at which the vehicle's position was measured. In POSIX time

// (i.e., number of seconds since January 1st 1970 00:00:00 UTC).

optional uint64 timestamp = 5;

// Congestion level that is affecting this vehicle.

enum CongestionLevel {

UNKNOWN_CONGESTION_LEVEL = 0;

RUNNING_SMOOTHLY = 1;

STOP_AND_GO = 2;

CONGESTION = 3;

SEVERE_CONGESTION = 4; // People leaving their cars.

}

optional CongestionLevel congestion_level = 6;

}

// An alert, indicating some sort of incident in the public transit network.

message Alert {

// Time when the alert should be shown to the user. If missing, the

// alert will be shown as long as it appears in the feed.

// If multiple ranges are given, the alert will be shown during all of them.

repeated TimeRange active_period = 1;

// Entities whose users we should notify of this alert.

repeated EntitySelector informed_entity = 5;

// Cause of this alert.

enum Cause {

UNKNOWN_CAUSE = 1;

OTHER_CAUSE = 2; // Not machine-representable.

TECHNICAL_PROBLEM = 3;

STRIKE = 4; // Public transit agency employees stopped working.

DEMONSTRATION = 5; // People are blocking the streets.

ACCIDENT = 6;

HOLIDAY = 7;

WEATHER = 8;

MAINTENANCE = 9;

CONSTRUCTION = 10;

POLICE_ACTIVITY = 11;

MEDICAL_EMERGENCY = 12;

}

optional Cause cause = 6 [default = UNKNOWN_CAUSE];

// What is the effect of this problem on the affected entity.

enum Effect {

NO_SERVICE = 1;

REDUCED_SERVICE = 2;

// We don't care about INsignificant delays: they are hard to detect, have

// little impact on the user, and would clutter the results as they are too

// frequent.

SIGNIFICANT_DELAYS = 3;

DETOUR = 4;

ADDITIONAL_SERVICE = 5;

MODIFIED_SERVICE = 6;

OTHER_EFFECT = 7;

UNKNOWN_EFFECT = 8;

STOP_MOVED = 9;

}

optional Effect effect = 7 [default = UNKNOWN_EFFECT];

// The URL which provides additional information about the alert.

optional TranslatedString url = 8;

// Alert header. Contains a short summary of the alert text.

optional TranslatedString header_text = 10;

// Full description for the alert. The information in the description

// should add to the information of the header.

optional TranslatedString description_text = 11;

}

//

// Low level data structures used above.

//

// A time interval.

message TimeRange {

// Start time, in POSIX time (i.e., number of seconds since January 1st 1970

// 00:00:00 UTC).

// If missing, the interval starts at minus infinity.

optional uint64 start = 1;

// End time, in POSIX time (i.e., number of seconds since January 1st 1970

// 00:00:00 UTC).

// If missing, the interval ends at plus infinity.

optional uint64 end = 2;

}

// A position.

message Position {

// Degrees North, in the WGS-84 coordinate system.

required float latitude = 1;

// Degrees East, in the WGS-84 coordinate system.

required float longitude = 2;

// Bearing, in degrees, clockwise from North, i.e., 0 is North and 90 is East.

// This can be the compass bearing, or the direction towards the next stop

// or intermediate location.

// This should not be direction deduced from the sequence of previous

// positions, which can be computed from previous data.

optional float bearing = 3;

// Odometer value, in meters.

optional double odometer = 4;

// Momentary speed measured by the vehicle, in meters per second.

optional float speed = 5;

	// Copyright 2010 Google Inc
	//
	// The content of this file is licensed under the Creative Commons Attribution
	// 3.0 License.
	//
	// Protocol definition file for GTFS-realtime.
	//
	// GTFS-realtime lets transit agencies provide consumers with realtime
	// information about disruptions to their service (stations closed, lines not
	// operating, important delays etc), location of their vehicles and expected
	// arrival times.
	//
	// This protocol is published on http://code.google.com/transit/realtime/ .

	syntax = "proto2";

	option cc_api_version = 2;
	option py_api_version = 1;

	option java_package = "com.google.transit.realtime";
	package transit_realtime;

	// The contents of a feed message.
	// A feed is a continuous stream of feed messages. Each message in the stream is
	// obtained as a response to an appropriate HTTP GET request.
	// A realtime feed is always defined with relation to an existing GTFS feed.
	// All the entity ids are resolved with respect to the GTFS feed.
	//
	// A feed depends on some external configuration:
	// - The corresponding GTFS feed.
	// - Feed application (updates, positions or alerts). A feed should contain only
	// items of one specified application; all the other entities will be ignored.
	// - Polling frequency
	message FeedMessage {
	// Metadata about this feed and feed message.
	required FeedHeader header = 1;

	// Contents of the feed.
	repeated FeedEntity entity = 2;
	}

	// Metadata about a feed, included in feed messages.
	message FeedHeader {
	// Version of the feed specification.
	// The current version is 1.0.
	required string gtfs_realtime_version = 1;

	// Determines whether the current fetch is incremental.
	enum Incrementality {
	FULL_DATASET = 0;
	DIFFERENTIAL = 1;
	}
	optional Incrementality incrementality = 2 [default = FULL_DATASET];

	// This timestamp identifies the moment when the content of this feed has been
	// created (in server time). In POSIX time (i.e., number of seconds since
	// January 1st 1970 00:00:00 UTC).
	optional uint64 timestamp = 3;
	}

	// A definition (or update) of an entity in the transit feed.
	message FeedEntity {
	// The ids are used only to provide incrementality support. The id should be
	// unique within a FeedMessage. Consequent FeedMessages may contain
	// FeedEntities with the same id. In case of a DIFFERENTIAL update the new
	// FeedEntity with some id will replace the old FeedEntity with the same id
	// (or delete it - see is_deleted below).
	// The actual GTFS entities (e.g. stations, routes, trips) referenced by the
	// feed must be specified by explicit selectors (see EntitySelector below for
	// more info).
	required string id = 1;

	// Whether this entity is to be deleted. Relevant only for incremental
	// fetches.
	optional bool is_deleted = 2 [default = false];

	// Data about the entity itself. Exactly one of the following fields must be
	// present (unless the entity is being deleted).
	optional TripUpdate trip_update = 3;
	optional VehiclePosition vehicle = 4;
	optional Alert alert = 5;
	}

	//
	// Entities used in the feed.
	//

	// Realtime update of the progress of a vehicle along a trip.
	// Depending on the value of ScheduleRelationship, a TripUpdate can specify:
	// - A trip that proceeds along the schedule.
	// - A trip that proceeds along a route but has no fixed schedule.
	// - A trip that have been added or removed with regard to schedule.
	//
	// The updates can be for future, predicted arrival/departure events, or for
	// past events that already occurred.
	// Normally, updates should get more precise and more certain (see
	// uncertainty below) as the events gets closer to current time.
	// Even if that is not possible, the information for past events should be
	// precise and certain. In particular, if an update points to time in the past
	// but its update's uncertainty is not 0, the client should conclude that the
	// update is a (wrong) prediction and that the trip has not completed yet.
	//
	// Note that the update can describe a trip that is already completed.
	// To this end, it is enough to provide an update for the last stop of the trip.
	// If the time of that is in the past, the client will conclude from that that
	// the whole trip is in the past (it is possible, although inconsequential, to
	// also provide updates for preceding stops).
	// This option is most relevant for a trip that has completed ahead of schedule,
	// but according to the schedule, the trip is still proceeding at the current
	// time. Removing the updates for this trip could make the client assume
	// that the trip is still proceeding.
	// Note that the feed provider is allowed, but not required, to purge past
	// updates - this is one case where this would be practically useful.
	message TripUpdate {
	// The Trip that this message applies to. There can be at most one
	// TripUpdate entity for each actual trip instance.
	// If there is none, that means there is no prediction information available.
	// It does not mean that the trip is progressing according to schedule.
	required TripDescriptor trip = 1;

	// Additional information on the vehicle that is serving this trip.
	optional VehicleDescriptor vehicle = 3;

	// Timing information for a single predicted event (either arrival or
	// departure).
	// Timing consists of delay and/or estimated time, and uncertainty.
	// - delay should be used when the prediction is given relative to some
	// existing schedule in GTFS.
	// - time should be given whether there is a predicted schedule or not. If
	// both time and delay are specified, time will take precedence
	// (although normally, time, if given for a scheduled trip, should be
	// equal to scheduled time in GTFS + delay).
	//
	// Uncertainty applies equally to both time and delay.
	// The uncertainty roughly specifies the expected error in true delay (but
	// note, we don't yet define its precise statistical meaning). It's possible
	// for the uncertainty to be 0, for example for trains that are driven under
	// computer timing control.
	message StopTimeEvent {
	// Delay (in seconds) can be positive (meaning that the vehicle is late) or
	// negative (meaning that the vehicle is ahead of schedule). Delay of 0
	// means that the vehicle is exactly on time.
	optional int32 delay = 1;

	// Event as absolute time.
	// In Unix time (i.e., number of seconds since January 1st 1970 00:00:00
	// UTC).
	optional int64 time = 2;

	// If uncertainty is omitted, it is interpreted as unknown.
	// If the prediction is unknown or too uncertain, the delay (or time) field
	// should be empty. In such case, the uncertainty field is ignored.
	// To specify a completely certain prediction, set its uncertainty to 0.
	optional int32 uncertainty = 3;
	}

	// Realtime update for arrival and/or departure events for a given stop on a
	// trip. Updates can be supplied for both past and future events.
	// The producer is allowed, although not required, to drop past events.
	message StopTimeUpdate {
	// The update is linked to a specific stop either through stop_sequence or
	// stop_id, so one of the fields below must necessarily be set.
	// See the documentation in TripDescriptor for more information.

	// Must be the same as in stop_times.txt in the corresponding GTFS feed.
	optional uint32 stop_sequence = 1;
	// Must be the same as in stops.txt in the corresponding GTFS feed.
	optional string stop_id = 4;

	optional StopTimeEvent arrival = 2;
	optional StopTimeEvent departure = 3;

	// The relation between this StopTime and the static schedule.
	enum ScheduleRelationship {
	// The vehicle is proceeding in accordance with its static schedule of
	// stops, although not necessarily according to the times of the schedule.
	// At least one of arrival and departure must be provided. If the schedule
	// for this stop contains both arrival and departure times then so must
	// this update. An update with only an arrival, say, where the schedule
	// has both, indicates that the trip is terminating early at this stop.
	SCHEDULED = 0;

	// The stop is skipped, i.e., the vehicle will not stop at this stop.
	// Arrival and departure are optional.
	SKIPPED = 1;

	// No data is given for this stop. The main intention for this value is to
	// give the predictions only for part of a trip, i.e., if the last update
	// for a trip has a NO_DATA specifier, then StopTimes for the rest of the
	// stops in the trip are considered to be unspecified as well.
	// Neither arrival nor departure should be supplied.
	NO_DATA = 2;
	}
	optional ScheduleRelationship schedule_relationship = 5
	[default = SCHEDULED];
	}

	// Updates to StopTimes for the trip (both future, i.e., predictions, and in
	// some cases, past ones, i.e., those that already happened).
	// The updates must be sorted by stop_sequence, and apply for all the
	// following stops of the trip up to the next specified one.
	//
	// Example 1:
	// For a trip with 20 stops, a StopTimeUpdate with arrival delay and departure
	// delay of 0 for stop_sequence of the current stop means that the trip is
	// exactly on time.
	//
	// Example 2:
	// For the same trip instance, 3 StopTimeUpdates are provided:
	// - delay of 5 min for stop_sequence 3
	// - delay of 1 min for stop_sequence 8
	// - delay of unspecified duration for stop_sequence 10
	// This will be interpreted as:
	// - stop_sequences 3,4,5,6,7 have delay of 5 min.
	// - stop_sequences 8,9 have delay of 1 min.
	// - stop_sequences 10,... have unknown delay.
	repeated StopTimeUpdate stop_time_update = 2;
	}

	// Realtime positioning information for a given vehicle.
	message VehiclePosition {
	// The Trip that this vehicle is serving.
	// Can be empty or partial if the vehicle can not be identified with a given
	// trip instance.
	optional TripDescriptor trip = 1;

	// Additional information on the vehicle that is serving this trip.
	optional VehicleDescriptor vehicle = 8;

	// Current position of this vehicle.
	optional Position position = 2;

	// The stop sequence index of the current stop. The meaning of
	// current_stop_sequence (i.e., the stop that it refers to) is determined by
	// current_status.
	// If current_status is missing IN_TRANSIT_TO is assumed.
	optional uint32 current_stop_sequence = 3;
	// Identifies the current stop. The value must be the same as in stops.txt in
	// the corresponding GTFS feed.
	optional string stop_id = 7;

	enum VehicleStopStatus {
	// The vehicle is just about to arrive at the stop (on a stop
	// display, the vehicle symbol typically flashes).
	INCOMING_AT = 0;

	// The vehicle is standing at the stop.
	STOPPED_AT = 1;

	// The vehicle has departed and is in transit to the next stop.
	IN_TRANSIT_TO = 2;
	}
	// The exact status of the vehicle with respect to the current stop.
	// Ignored if current_stop_sequence is missing.
	optional VehicleStopStatus current_status = 4 [default = IN_TRANSIT_TO];

	// Moment at which the vehicle's position was measured. In POSIX time
	// (i.e., number of seconds since January 1st 1970 00:00:00 UTC).
	optional uint64 timestamp = 5;

	// Congestion level that is affecting this vehicle.
	enum CongestionLevel {
	UNKNOWN_CONGESTION_LEVEL = 0;
	RUNNING_SMOOTHLY = 1;
	STOP_AND_GO = 2;
	CONGESTION = 3;
	SEVERE_CONGESTION = 4; // People leaving their cars.
	}
	optional CongestionLevel congestion_level = 6;
	}

	// An alert, indicating some sort of incident in the public transit network.
	message Alert {
	// Time when the alert should be shown to the user. If missing, the
	// alert will be shown as long as it appears in the feed.
	// If multiple ranges are given, the alert will be shown during all of them.
	repeated TimeRange active_period = 1;

	// Entities whose users we should notify of this alert.
	repeated EntitySelector informed_entity = 5;

	// Cause of this alert.
	enum Cause {
	UNKNOWN_CAUSE = 1;
	OTHER_CAUSE = 2; // Not machine-representable.
	TECHNICAL_PROBLEM = 3;
	STRIKE = 4; // Public transit agency employees stopped working.
	DEMONSTRATION = 5; // People are blocking the streets.
	ACCIDENT = 6;
	HOLIDAY = 7;
	WEATHER = 8;
	MAINTENANCE = 9;
	CONSTRUCTION = 10;
	POLICE_ACTIVITY = 11;
	MEDICAL_EMERGENCY = 12;
	}
	optional Cause cause = 6 [default = UNKNOWN_CAUSE];

	// What is the effect of this problem on the affected entity.
	enum Effect {
	NO_SERVICE = 1;
	REDUCED_SERVICE = 2;

	// We don't care about INsignificant delays: they are hard to detect, have
	// little impact on the user, and would clutter the results as they are too
	// frequent.
	SIGNIFICANT_DELAYS = 3;

	DETOUR = 4;
	ADDITIONAL_SERVICE = 5;
	MODIFIED_SERVICE = 6;
	OTHER_EFFECT = 7;
	UNKNOWN_EFFECT = 8;
	STOP_MOVED = 9;
	}
	optional Effect effect = 7 [default = UNKNOWN_EFFECT];

	// The URL which provides additional information about the alert.
	optional TranslatedString url = 8;

	// Alert header. Contains a short summary of the alert text.
	optional TranslatedString header_text = 10;

	// Full description for the alert. The information in the description
	// should add to the information of the header.
	optional TranslatedString description_text = 11;
	}

	//
	// Low level data structures used above.
	//

	// A time interval.
	message TimeRange {
	// Start time, in POSIX time (i.e., number of seconds since January 1st 1970
	// 00:00:00 UTC).
	// If missing, the interval starts at minus infinity.
	optional uint64 start = 1;

	// End time, in POSIX time (i.e., number of seconds since January 1st 1970
	// 00:00:00 UTC).
	// If missing, the interval ends at plus infinity.
	optional uint64 end = 2;
	}

	// A position.
	message Position {
	// Degrees North, in the WGS-84 coordinate system.
	required float latitude = 1;

	// Degrees East, in the WGS-84 coordinate system.
	required float longitude = 2;

	// Bearing, in degrees, clockwise from North, i.e., 0 is North and 90 is East.
	// This can be the compass bearing, or the direction towards the next stop
	// or intermediate location.
	// This should not be direction deduced from the sequence of previous
	// positions, which can be computed from previous data.
	optional float bearing = 3;

	// Odometer value, in meters.
	optional double odometer = 4;
	// Momentary speed measured by the vehicle, in meters per second.
	optional float speed = 5;