The file consist of three sections written after each other:

• Header
• Basic data
• Data event list And is closed with an end-of-file marker.

Data types

All integers (16, 32 and 64 bit) are stored as big-endians. All floats (32 and 64 bit) are stored in IEEE 754 format. Their bit-represenation is stored as big-endians.

Field data format

A 'field' is a data structure used in the file.

Offset	Size	Value	Meaning
0	1 Byte	'#'	Start-of-the-Field marker.
1	2 Bytes	integer	Field identifier.
3	4 Bytes	integer	Length of the data.
7	equal to "Length of the data"		The contained data.

Header

Offset	Size	Value	Meaning
0	20 Bytes	"//MILTSCHEK/TRACKER/"	File type identifier.
20	2 Bytes	integer = 2	Version of the file.

Basic data

Consists of any number of 'fields' with identifiers between 0x1000 and 0x1fff.

Id	Description	Length (bytes)	Data type	Units
0x1001	Real-time-clock timestamp of the beginning of the sport activity.	8	long integer	milliseconds since Jan, 1st 1970
0x1002	Real-time-clock timestamp of the end of the sport activity.	8	long integer	milliseconds since Jan, 1st 1979
0x1003	Ticks timestamp of the beginning of the sport activity (relevant for comparison of sensor events' timestamps).	8	long integer	nanoseconds abstract
0x1004	Ticks timestamp of the end of the sport activity (relevant for comparison of sensor events' timestamps).	8	long integer	nanoseconds abstract
0x1011	Average heart rate during the sport activity.	4	float	beats per minute
0x1012	Maximum heart rate during the sport activity.	4	integer	beats per minute
0x1013	Total number of steps during the sport activity.	4	integer	number
0x1014	Average steps rate during the sport activity.	4	float	steps per minute
0x1015	Total ascent during the sport activity (using GNSS data).	4	float	meters
0x1016	Total descent during the sport activity (using GNSS data).	4	float	meters
0x1017	Average speed during the sport activity (using GNSS data).	4	float	meters per second

Data event list

Consists of any number of 'fields' with identifiers between 0x2000 and 0x2fff. The data area of each field usually contain multiple values stored after each other with no additional separators.

Id	Description	Length (bytes)	Data type	Value	Units
0x2011	Heart rate sensor event.	8	long integer	Timestamp of the event (comparable to 0x1003 and 0x1004).	nanoseconds abstract
		4	integer	Measured heart rate.	beats per minute
		4	integer	Sensor accuracy.	See: Sensor accuracy.
0x2021	Steps counter event.	8	long integer	Timestamp of the event (comparable to 0x1003 and 0x1004).	nanoseconds abstract
		4	integer	Steps counter state (always total amount of steps since sensor reset).	number
		4	integer	Sensor accuracy.	See: Sensor accuracy.
0x2031	Air pressure sensor event.	8	long integer	Timestamp of the event (comparable to 0x1003 and 0x1004).	nanoseconds abstract
		4	float	Measured air pressure.	millibars
		4	integer	Sensor accuracy.	See: Sensor accuracy.
0x2041	Geo (GNSS) sensor event.	8	long integer	Timestamp of the event (comparable to 0x1003 and 0x1004).	nanoseconds abstract
		8	long integer	Timestamp of the fix (ticks, comparable to 0x1003 and 0x1004).	nanoseconds abstract
		8	long integer	Real-time-clock timestamp of the fix.	milliseconds since Jan, 1st 1970
		8	double	Latitude.	degrees
		8	double	Longitude.	degrees
		4	float	Lateral accuracy.	meters
		8	double	Altitude.	meters
		4	float	Bearing.	degrees
		4	float	Speed.	meters per second
		4	integer	Sensor accuracy. Not used for GNSS.	See: Sensor accuracy.

End-of-File marker

The marker is a 'field' of the identifier = 0xffff and an empty data area (length value = 0).

Id	Description	Length (bytes)	Data type	Units
0xffff	End-of-file marker.	0	n/a	n/a

Sensor accuracy

---

Some sensors do report the measurement accuracy. The summary values (e.g. average heart rate) are calculated on events of at least low accuracy.

Value	Meaning
-1	Measurement not to be trusted as the sensor did not have a contact with what it was supposed to measure.
0	Measurement is unreliable (e.g. uncalibrated).
1	Low accuracy (e.g. calibration needed).
2	Medium accuracy (e.g. calibration could improve the readings).
3	High accuracy (maximum available for the sensor).