ISO 13526:2010

INTERNATIONAL ISO
STANDARD 13526
First edition
2010-09-15
Space data and information transfer
systems — Tracking data message
Systèmes de transfert des informations et données spatiales —
Message de données de suivi
Reference number
©
ISO 2010
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ii © ISO 2010 – All rights reserved

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 13526 was prepared by the Consultative Committee for Space Data Systems (CCSDS) (as
CCSDS 503.0-B-1, November 2007) and was adopted (without modifications except those stated in Clause 2
of this International Standard) by Technical Committee ISO/TC 20, Aircraft and space vehicles, Subcommittee
SC 13, Space data and information transfer systems.

INTERNATIONAL STANDARD ISO 13526:2010(E)

Space data and information transfer systems — Tracking data
message
1 Scope
This International Standard specifies a standard message format for use in exchanging spacecraft tracking
data between space agencies. Such exchanges are used for distributing tracking data output from routine
interagency cross-supports, in which spacecraft missions managed by one agency are tracked from a ground
station managed by a second agency. The standardization of tracking data formats facilitates space agency
allocation of tracking sessions to alternate tracking resources.
This International Standard includes requirements and criteria that the message format has been designed to
meet. For exchanges where these requirements do not capture the needs of the participating agencies,
another mechanism can be selected.
The scope and field of application are furthermore detailed in subclause 1.2 of the enclosed CCSDS
publication.
2 Requirements
Requirements are the technical recommendations made in the following publication (reproduced on the
following pages), which is adopted as an International Standard:
CCSDS 503.0-B-1, November 2007, Tracking data message
For the purposes of international standardization, the modifications outlined below shall apply to the specific
clauses and paragraphs of publication CCSDS 503.0-B-1.
Pages i to v
This part is information which is relevant to the CCSDS publication only.
Page 1-4
Add the following information to the reference indicated:
[3] Document CCSDS 301.0-B-3, January 2002, is equivalent to ISO 11104:2003.
[4] Document CCSDS 502.0-B-1, September 2004, is equivalent to ISO 22644:2006.
Page E-1
Add the following information to the reference indicated:
1)
[E2] Document CCSDS 501.0-B-1-S, January 1987, is equivalent to ISO 11103:1991 .

1) Withdrawn in 2007.
3 Revision of publication CCSDS 503.0-B-1
It has been agreed with the Consultative Committee for Space Data Systems that Subcommittee
ISO/TC 20/SC 13 will be consulted in the event of any revision or amendment of publication
CCSDS 503.0-B-1. To this end, NASA will act as a liaison body between CCSDS and ISO.

2 © ISO 2010 – All rights reserved

Recommendation for Space Data System Standards
TRACKING DATA
MESSAGE
RECOMMENDED STANDARD
CCSDS 503.0-B-1
BLUE BOOK
November 2007
(blank page)
4 © ISO 2010 – All rights reserved

CCSDS RECOMMENDED STANDARD FOR TRACKING DATA MESSAGE
AUTHORITY
Issue: Recommended Standard, Issue 1
Date: November 2007
Location: Washington, DC, USA
This document has been approved for publication by the Management Council of the
Consultative Committee for Space Data Systems (CCSDS) and represents the consensus
technical agreement of the participating CCSDS Member Agencies. The procedure for
review and authorization of CCSDS Recommendations is detailed in the Procedures Manual
for the Consultative Committee for Space Data Systems, and the record of Agency
participation in the authorization of this document can be obtained from the CCSDS
Secretariat at the address below.

This document is published and maintained by:

CCSDS Secretariat
Space Communications and Navigation Office, 7L70
Space Operations Mission Directorate
NASA Headquarters
Washington, DC 20546-0001, USA

CCSDS 503.0-B-1 Page i November 2007
CCSDS RECOMMENDED STANDARD FOR TRACKING DATA MESSAGE
STATEMENT OF INTENT
The Consultative Committee for Space Data Systems (CCSDS) is an organization officially
established by the management of its members. The Committee meets periodically to address
data systems problems that are common to all participants, and to formulate sound technical
solutions to these problems. Inasmuch as participation in the CCSDS is completely
voluntary, the results of Committee actions are termed Recommended Standards and are
not considered binding on any Agency.
This Recommended Standard is issued by, and represents the consensus of, the CCSDS
members. Endorsement of this Recommendation is entirely voluntary. Endorsement,
however, indicates the following understandings:
o Whenever a member establishes a CCSDS-related standard, this standard will be in
accord with the relevant Recommended Standard. Establishing such a standard
does not preclude other provisions which a member may develop.
o Whenever a member establishes a CCSDS-related standard, that member will
provide other CCSDS members with the following information:
-- The standard itself.
-- The anticipated date of initial operational capability.
-- The anticipated duration of operational service.
o Specific service arrangements shall be made via memoranda of agreement. Neither
this Recommended Standard nor any ensuing standard is a substitute for a
memorandum of agreement.
No later than five years from its date of issuance, this Recommended Standard will be
reviewed by the CCSDS to determine whether it should: (1) remain in effect without change;
(2) be changed to reflect the impact of new technologies, new requirements, or new
directions; or (3) be retired or canceled.
In those instances when a new version of a Recommended Standard is issued, existing
CCSDS-related member standards and implementations are not negated or deemed to be
non-CCSDS compatible. It is the responsibility of each member to determine when such
standards or implementations are to be modified. Each member is, however, strongly
encouraged to direct planning for its new standards and implementations towards the later
version of the Recommended Standard.
CCSDS 503.0-B-1 Page ii November 2007
6 © ISO 2010 – All rights reserved

CCSDS RECOMMENDED STANDARD FOR TRACKING DATA MESSAGE
FOREWORD
This document is a Recommended Standard for tracking data messages and has been
prepared by the Consultative Committee for Space Data Systems (CCSDS). The tracking
data message described in this Recommended Standard is the baseline concept for tracking
data interchange applications that are cross-supported between Agencies of the CCSDS.
This Recommended Standard establishes a common framework and provides a common
basis for the format of tracking data exchange between space agencies. It allows
implementing organizations within each Agency to proceed coherently with the development
of compatible derived standards for the flight and ground systems that are within their
cognizance. Derived Agency standards may implement only a subset of the optional features
allowed by the Recommended Standard and may incorporate features not addressed by this
Recommended Standard.
Through the process of normal evolution, it is expected that expansion, deletion or
modification to this document may occur. This Recommended Standard is therefore subject
to CCSDS document management and change control procedures, as defined in the
Procedures Manual for the Consultative Committee for Space Data Systems. Current
versions of CCSDS documents are maintained at the CCSDS Web site:
http://www.ccsds.org/
Questions relating to the contents or status of this document should be addressed to the
CCSDS Secretariat at the address indicated on page i.
CCSDS 503.0-B-1 Page iii November 2007
CCSDS RECOMMENDED STANDARD FOR TRACKING DATA MESSAGE
At time of publication, the active Member and Observer Agencies of the CCSDS were:

Member Agencies
– Agenzia Spaziale Italiana (ASI)/Italy.
– British National Space Centre (BNSC)/United Kingdom.
– Canadian Space Agency (CSA)/Canada.
– Centre National d’Etudes Spatiales (CNES)/France.
– Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR)/Germany.
– European Space Agency (ESA)/Europe.
– Federal Space Agency (FSA)/Russian Federation.
– Instituto Nacional de Pesquisas Espaciais (INPE)/Brazil.
– Japan Aerospace Exploration Agency (JAXA)/Japan.
– National Aeronautics and Space Administration (NASA)/USA.

Observer Agencies
– Austrian Space Agency (ASA)/Austria.
– Belgian Federal Science Policy Office (BFSPO)/Belgium.
– Central Research Institute of Machine Building (TsNIIMash)/Russian Federation.
– Centro Tecnico Aeroespacial (CTA)/Brazil.
– Chinese Academy of Sciences (CAS)/China.
– Chinese Academy of Space Technology (CAST)/China.
– Commonwealth Scientific and Industrial Research Organization (CSIRO)/Australia.
– Danish National Space Center (DNSC)/Denmark.
– European Organization for the Exploitation of Meteorological Satellites
(EUMETSAT)/Europe.
– European Telecommunications Satellite Organization (EUTELSAT)/Europe.
– Hellenic National Space Committee (HNSC)/Greece.
– Indian Space Research Organization (ISRO)/India.
– Institute of Space Research (IKI)/Russian Federation.
– KFKI Research Institute for Particle & Nuclear Physics (KFKI)/Hungary.
– Korea Aerospace Research Institute (KARI)/Korea.
– MIKOMTEK: CSIR (CSIR)/Republic of South Africa.
– Ministry of Communications (MOC)/Israel.
– National Institute of Information and Communications Technology (NICT)/Japan.
– National Oceanic and Atmospheric Administration (NOAA)/USA.
– National Space Organization (NSPO)/Taiwan.
– Naval Center for Space Technology (NCST)/USA.
– Space and Upper Atmosphere Research Commission (SUPARCO)/Pakistan.
– Swedish Space Corporation (SSC)/Sweden.
– United States Geological Survey (USGS)/USA.

CCSDS 503.0-B-1 Page iv November 2007
8 © ISO 2010 – All rights reserved

CCSDS RECOMMENDED STANDARD FOR TRACKING DATA MESSAGE
DOCUMENT CONTROL
Document Title Date Status
CCSDS Tracking Data Message, November Original issue
503.0-B-1 Recommended Standard, Issue 1 2007

CCSDS 503.0-B-1 Page v November 2007
CCSDS RECOMMENDED STANDARD FOR TRACKING DATA MESSAGE
CONTENTS
Section Page
1 INTRODUCTION. 1-1
1.1 PURPOSE.1-1
1.2 SCOPE AND APPLICABILITY. 1-1
1.3 CONVENTIONS AND DEFINITIONS. 1-2
1.4 STRUCTURE OF THIS DOCUMENT. 1-3
1.5 REFERENCES.1-4
2 OVERVIEW. 2-1
2.1 GENERAL.2-1
2.2 THE TRACKING DATA MESSAGE (TDM) BASIC CONTENT . 2-1
3 TRACKING DATA MESSAGE STRUCTURE AND CONTENT. 3-1
3.1 GENERAL.3-1
3.2 TDM HEADER.3-3
3.3 TDM METADATA.3-5
3.4 TDM DATA SECTION (GENERAL SPECIFICATION). 3-19
3.5 TDM DATA SECTION KEYWORDS. 3-23
4 TRACKING DATA MESSAGE SYNTAX . 4-1
4.1 GENERAL.4-1
4.2 TDM LINES.4-1
4.3 TDM VALUES.4-2
4.4 UNITS IN THE TDM. 4-3
4.5 COMMENTS IN A TDM. 4-4
5 SECURITY. 5-1
5.1 OVERVIEW.5-1
5.2 SECURITY CONCERNS RELATED TO THIS RECOMMENDED STANDARD5-1
5.3 POTENTIAL THREATS AND ATTACK SCENARIOS . 5-2
5.4 CONSEQUENCES OF NOT APPLYING SECURITY TO THE TECHNOLOGY5-2
5.5 DATA SECURITY IMPLEMENTATION SPECIFICS. 5-2

CCSDS 503.0-B-1 Page vi November 2007
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CCSDS RECOMMENDED STANDARD FOR TRACKING DATA MESSAGE
CONTENTS (CONTINUED)
Section Page
ANNEX A VALUES FOR TIME_SYSTEM AND REFERENCE_FRAME
(NORMATIVE) . A-1
ANNEX B ITEMS FOR AN INTERFACE CONTROL DOCUMENT
(INFORMATIVE) .B-1
ANNEX C ABBREVIATIONS AND ACRONYMS (INFORMATIVE). C-1
ANNEX D EXAMPLE TRACKING DATA MESSAGES (INFORMATIVE) . D-1
ANNEX E INFORMATIVE REFERENCES (INFORMATIVE) .E-1
ANNEX F RATIONALE FOR TRACKING DATA MESSAGES
(INFORMATIVE) .F-1
ANNEX G TDM SUMMARY SHEET (INFORMATIVE) . G-1

Figure
D-1 TDM Example: One-Way Data . D-1
D-2 TDM Example: One-Way Data w/Frequency Offset . D-2
D-3 TDM Example: Two-Way Frequency Data for Doppler Calculation . D-3
D-4 TDM Example: Two-Way Ranging Data Only. D-4
D-5 TDM Example: Three-Way Frequency Data. D-5
D-6 TDM Example: Four-Way Data . D-6
D-7 TDM Example: One S/C, X-up, S-down, X-down, Ka-down, Three Segments . D-7
D-8 TDM Example: Angles, Range, Doppler Combined in Single TDM. D-8
D-9 TDM Example: Range Data with TIMETAG_REF=TRANSMIT . D-9
D-10 TDM Example: Differenced Doppler Observable. D-10
D-11 TDM Example: Delta-DOR Observable. D-11
D-12 TDM Example: Angle Data Only. D-12
D-13 TDM Example: Media Data Only . D-13
D-14 TDM Example: Meteorological Data Only . D-14
D-15 TDM Example: Clock Bias/Drift Only. D-15

Table
3-1 TDM Structure. 3-2
3-2 TDM Header. 3-3
3-3 TDM Metadata Section. 3-7
3-4 Tracking Data Record Generic Format. 3-19
3-5 Summary Table of TDM Data Section Keywords (Alpha Order). 3-24
3-6 Summary Table of TDM Data Section Keywords (Category Order). 3-25
F-1 Primary Requirements .F-2
F-2 Heritage Requirements .F-3
F-3 Desirable Characteristics .F-3

CCSDS 503.0-B-1 Page vii November 2007
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CCSDS RECOMMENDED STANDARD FOR TRACKING DATA MESSAGE
1 INTRODUCTION
1.1 PURPOSE
1.1.1 This Tracking Data Message (TDM) Recommended Standard specifies a standard
message format for use in exchanging spacecraft tracking data between space agencies. Such
exchanges are used for distributing tracking data output from routine interagency cross-
supports in which spacecraft missions managed by one agency are tracked from a ground
station managed by a second agency. The standardization of tracking data formats facilitates
space agency allocation of tracking sessions to alternate tracking resources. This
Recommended Standard has been developed via consensus of the Navigation Working
Group of the CCSDS Mission Operations and Information Management Services (MOIMS)
area.
1.1.2 This document includes requirements and criteria that the message format has been
designed to meet. For exchanges where these requirements do not capture the needs of the
participating Agencies another mechanism may be selected.
1.2 SCOPE AND APPLICABILITY
1.2.1 This Recommended Standard contains the specification for a Tracking Data Message
designed for applications involving tracking data interchange between space data systems.
Tracking data includes data types such as Doppler, transmit/received frequencies, range,
angles, Delta-DOR, DORIS, PRARE, media correction, weather, etc. The rationale behind the
design of the message is described in annex F and may help the application engineer construct a
suitable message. It is acknowledged that this version of the Recommended Standard may not
apply to every single tracking session or data type; however, it is desired to focus on covering
approximately the ‘95% level’ of tracking scenarios, and to expand the coverage in future
versions as experience with the TDM is gained.
1.2.2 This message is suited to inter-agency exchanges that involve automated interaction.
The attributes of a TDM make it primarily suitable for use in computer-to-computer
communication because of the large amount of data typically present. The TDM is self-
contained, with no additional information required beyond that specified in an Interface
Control Document (ICD) written jointly by the service provider and customer agency.
1.2.3 Definition of the accuracy pertaining to any particular TDM is outside the scope of
this Recommended Standard and should be specified via an Interface Control Document
(ICD) between data exchange participants.
1.2.4 This Recommended Standard is applicable only to the message format and content, but
not to its transmission. The method of transmitting the message between exchange partners is
beyond the scope of this document and should be specified in the ICD. Message transmission
could be based on a CCSDS data transfer protocol, file based transfer protocol such as SFTP,
stream-oriented media, or other secure transmission mechanism. In general, the transmission
mechanism must not place constraints on the technical data content of a TDM.
CCSDS 503.0-B-1 Page 1-1 November 2007
CCSDS RECOMMENDED STANDARD FOR TRACKING DATA MESSAGE
1.2.5 There are some specific exclusions to the TDM, as listed below:
1.2.5.1 Satellite Laser Ranging (SLR) ‘Fullrate’ and/or ‘Normal Points’ format (sometimes
referred to as ‘Quicklook’), which are already transferred via a standardized format
documented at http://ilrs.gsfc.nasa.gov/;
1.2.5.2 Exchanges of raw Global Navigation Satellite System (GNSS) data, which is
standardized via the RINEX format (http://gps.wva.net/html.common/rinex.html);
1.2.5.3 Global Positioning Satellite (GPS) navigation solutions, which are standardized via
the SP3 format (http://www.ngs.noaa.gov/GPS/GPS.html);
1.2.5.4 Optical data from navigation cameras (pixel based, row-column, etc.);
1.2.5.5 LIDAR data (which may include a laser range finder); however, such data could
conceivably be transferred via TDM with a ‘RANGE’ keyword (see 3.5.2.6); and
1.2.5.6 Altimeter data; however, such data could conceivably be transferred via TDM with
a ‘RANGE’ keyword (see 3.5.2.6).
1.2.6 Description of the message format based on the use of eXtensible Markup Language
(XML) is detailed in an integrated XML schema document for all Navigation Data Message
Recommendations: Attitude Data Messages (ADM), Orbit Data Messages (ODM), and
Tracking Data Message (TDM). See reference [E8].
1.3 CONVENTIONS AND DEFINITIONS
1.3.1 Conventions and definitions of navigation concepts such as reference frames, time
systems, etc., are provided in reference [1].
1.3.2 The following conventions apply throughout this Recommended Standard:
– the words ‘shall’ and ‘must’ imply a binding and verifiable specification;
– the word ‘should’ implies an optional, but desirable, specification;
– the word ‘may’ implies an optional specification;
– the words ‘is’, ‘are’, and ‘will’ imply statements of fact.

It has been suggested that the statement regarding navigation solutions being standardized by SP3 is not
correct, because SP3 prescribes equidistant data (ephemerides), which are in general not provided by each
GPS/GNSS receiver. It was proposed that the navigation solution data (epoch, x, y, z, v , v , v ) should be
x y z
provided in the TDM, with the velocities as optional values. However, this would require major changes to the
TDM that are contrary to its intended purpose. As an alternative, the CCSDS Orbit Data Messages OEM (Orbit
Ephemeris Message) (reference [4]) could be used to convey the navigation solution if all position and velocity
components are transferred. The OEM is already set up to convey all the required values, and can be used to
convey orbit reconstructions as well as orbit predictions.
CCSDS 503.0-B-1 Page 1-2 November 2007
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CCSDS RECOMMENDED STANDARD FOR TRACKING DATA MESSAGE
– The word ‘participant’ denotes an entity that has the ability to acquire or broadcast
navigation messages and/or radio frequencies, for example, a spacecraft, a quasar, a
tracking station, a tracking instrument, or an agency.
– The term ‘n/a’ or ‘N/A’ denotes an attribute that is not applicable or not available.
1.3.3 The following conventions for unit notations apply throughout this Recommended
Standard. Insofar as possible, an effort has been made to use units that are part of the
International System of Units (SI Units); units are either SI base units, SI derived units, or
units outside the SI that are accepted for use with the SI (see reference [8]). There are a
small number of specific cases where units that are more widely used in the navigation
community are specified, but every effort has been made to minimize these departures from
the SI.
%: per cent
dBHz: decibels referenced to one Hz
dBW: decibels referenced to one Watt
deg: degrees of plane angle
hPa: hectoPascal
Hz: Hertz
K: degrees Kelvin
km: kilometers
m: meters
RU: range units
s: seconds
TECU: Total Electron Count Units
1.4 STRUCTURE OF THIS DOCUMENT
1.4.1 Section 2 provides a brief overview of the CCSDS-recommended Tracking Data
Message (TDM).
1.4.2 Section 3 provides details about the structure and content of the TDM.
1.4.3 Section 4 provides details about the syntax used in the TDM.
1.4.4 Section 5 discusses security considerations for the TDM.
1.4.5 Annex A provides a normative list of approved values for selected TDM Metadata
Section keywords.
1.4.6 Annex B lists a number of items that should be covered in interagency ICDs prior to
exchanging TDMs on a regular basis. There are several statements throughout the document
that refer to the desirability or necessity of such a document; this annex consolidates all the
suggested ICD items in a single list.
CCSDS 503.0-B-1 Page 1-3 November 2007
CCSDS RECOMMENDED STANDARD FOR TRACKING DATA MESSAGE
1.4.7 Annex C is a list of abbreviations and acronyms applicable to the TDM.
1.4.8 Annex D shows how various tracking scenarios can be accommodated using the
TDM, via several examples.
1.4.9 Annex E contains a list of informative references.
1.4.10 Annex F lists a set of requirements and desirable characteristics that were taken into
consideration in the design of the TDM.
1.4.11 Annex G provides a TDM Summary Sheet, or ‘Quick Reference’.
1.5 REFERENCES
The following documents contain provisions which, through reference in this text, constitute
provisions of this Recommended Standard. At the time of publication, the editions indicated
were valid. All documents are subject to revision, and users of this Recommended Standard
are encouraged to investigate the possibility of applying the most recent editions of the
documents indicated below. The CCSDS Secretariat maintains a register of currently valid
CCSDS Recommended Standards.
[1] Navigation Data—Definitions and Conventions. Report Concerning Space Data
System Standards, CCSDS 500.0-G-2. Green Book. Issue 2. Washington, D.C.:
CCSDS, November 2005.
[2] Information Technology—8-Bit Single-Byte Coded Graphic Character Sets—Part 1:
Latin Alphabet No. 1. International Standard, ISO/IEC 8859-1:1998. Geneva: ISO,
1998.
[3] Time Code Formats. Recommendation for Space Data System Standards, CCSDS
301.0-B-3. Blue Book. Issue 3. Washington, D.C.: CCSDS, January 2002.
[4] Orbit Data Messages. Recommendation for Space Data System Standards, CCSDS
502.0-B-1. Blue Book. Issue 1. Washington, D.C.: CCSDS, September 2004.
[5] Spacewarn Bulletin. Greenbelt, MD, USA: WDC-SI.
[6] XML Schema Part 2: Datatypes. 2nd ed. P. Biron and A. Malhotra, eds. W3C
Recommendation 28. n.p.: W3C, 2004.
[7] IEEE Standard for Binary Floating-Point Arithmetic. IEEE Std 754-1985. New York:
IEEE, 1985.
[8] “The NIST Reference on Constants, Units, and Uncertainty.” NIST Physics
Laboratory. 
NOTE – Informative references are provided in annex E.
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CCSDS RECOMMENDED STANDARD FOR TRACKING DATA MESSAGE
2 OVERVIEW
2.1 GENERAL
This section provides a high-level overview of the CCSDS recommended Tracking Data
Message, a message format designed to facilitate standardized exchange of spacecraft
tracking data between space agencies.
2.2 THE TRACKING DATA MESSAGE (TDM) BASIC CONTENT
2.2.1 The TDM is realized as a sequence of plain ASCII text lines (reference [2]), which
may be in either a file format or a real-time stream. The content is separated into three basic
types of computer data structure as described in section 3.  The TDM architecture takes into
account that some aspects of tracking data change on a measurement-by-measurement basis
(data); some aspects change less frequently, but perhaps several times per track (metadata);
and other aspects change only rarely, e.g., once per track or perhaps less frequently (header).
The TDM makes it possible to convey a variety of tracking data used in the orbit
determination process in a single data message (e.g., standard Doppler and range
radiometrics in a variety of tracking modes, VLBI data, antenna pointing angles, etc.). To
aid in precision trajectory modeling, additional ancillary information may be included within
a TDM if it is desired and/or available (e.g., media corrections, meteorological data, clock
data, and other ancillary data). Facilities for documenting comments are provided.
2.2.2 The Tracking Data Message in this version of the Recommended Standard is ASCII-
text formatted. While binary-based tracking data message formats are computer efficient and
minimize overhead during data transfer, there are ground-segment applications for which an
ASCII character-based message is more appropriate. For example, ASCII format character-
based tracking data representations are useful in transferring data between heterogeneous
computing systems, because the ASCII character set is nearly universally used and is
interpretable by all popular systems. In addition, direct human-readable dumps of text to
displays, emails, documents or printers are possible without preprocessing. The penalty for
this convenience is some measure of inefficiency (based on early tests, such penalty would
be greatly reduced if the data is compressed for transmission).
2.2.3 The ASCII text in a TDM can be exchanged in either of two formats: a ‘keyword-
value notation’ format (KVN) or an XML format. The KVN formatted TDM is described in
this document. Description of the message format based on XML is detailed in an integrated
XML schema document for all Navigation Data Messages (reference [E8]). Exchange
participants should specify in the ICD which TDM ASCII format will be exchanged, the
KVN or the XML format.
2.2.4 Normally a TDM will contain tracking data for a single spacecraft participant, unless
the tracking session is spacecraft-to-spacecraft in nature. If a tracking operation involves
information from multiple spacecraft participants tracked from the ground, the data may be
included in a single TDM by using multiple segments (see 3.1); or multiple TDMs may be
used, one per spacecraft participant.
CCSDS 503.0-B-1 Page 2-1 November 2007
CCSDS RECOMMENDED STANDARD FOR TRACKING DATA MESSAGE
2.2.5 For a given spacecraft participant, multiple tracking data messages may be provided
in a message exchange session to achieve the tracking data requirements of the participating
agencies (e.g., launch supports with periodically delivered TDMs, or other critical events
such as maneuvers, encounters, etc.).
2.2.6 Provisions for the frequency of exchange and special types of exchanges should be
specified in an ICD.
CCSDS 503.0-B-1 Page 2-2 November 2007
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CCSDS RECOMMENDED STANDARD FOR TRACKING DATA MESSAGE
3 TRACKING DATA MESSAGE STRUCTURE AND CONTENT
3.1 GENERAL
3.1.1 The TDM shall consist of digital data represented as ASCII text lines (see reference [2])
in KVN format (Keyword = Value Notation—see section 4). The lines constituting a TDM
shall be represented as a combination of:
a) a Header (see 3.2);
b) a Metadata Section (data about data) (see 3.3); and
c) a Data Section (tracking data represented as ‘Tracking Data Records’) (see 3.4).
Optional comments may appear in specified locations in the Header, Metadata, and Data
Sections (see 4.5).
3.1.2 Taken together, the Metadata Section and its associated Data Section shall be called a
TDM Segment.
3.1.3 Each TDM shall have a Header and a Body.  The TDM Body shall consist of one or
more TDM Segments. There shall be no limit to the number of Segments in a given TDM
Body, beyond practical constraints, as shown in table 3-1.  Each Segment shall consist of a
Metadata Section and a Data Section that consists of a minimum of one Tracking Data
Record. Therefore, the overall structure of the TDM shall be:
– TDM = Header + Body;
– Body = Segment [+ Segment + . + Segment];
– Segment = Metadata Section + Data Section;
– Data Section = Tracking Data Record (TDR) [ + TDR + TDR … + TDR].
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CCSDS RECOMMENDED STANDARD FOR TRACKING DATA MESSAGE
Table 3-1: TDM Structure
Item  Obligatory?
Header  Yes
Body Segment 1 Metadata 1 Yes
Data 1
Segment 2 Metadata 2
No
Data 2
. . .
. . .
. . .
Segment n Metadata n
No
Data n
3.1.4 The TDM shall consist of tracking data for one or more tracking participants at
multiple epochs contained within a specified time range. (Note that the term ‘participant’
applies equally to spacecraft, quasars, tracking stations, and agency centers, as discussed in
reference [1]. Thus there may exist Tracking Data Messages for which there is no applicable
spacecraft.) Generally, but not necessarily, the time range of a TDM may correspond to a
‘tracking pass’.
3.1.5 The TDM shall be easily readable by both humans and computers.
3.1.6 It shall be possible to exchange a TDM either as a real-time stream or as a file.
3.1.7 The TDM file naming scheme shall be agreed to on a case-by-case basis between the
participating agencies, typically specified in an ICD. In general, the file name syntax and
length must not violate computer constraints for those computing environments in use by
Member Agencies for processing tracking data.
3.1.8 The method of exchanging TDMs shall be decided on a case-by-case basis by the
participating agencies and documented in an ICD. The exchange method shall not constrain
the tracking data content.
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CCSDS RECOMMENDED STANDARD FOR TRACKING DATA MESSAGE
3.2 TDM HEADER
3.2.1 The TDM shall include a Header that consists of information that identifies the basic
parameters of the message. The first Header line must be the first non-blank line in the
message.
3.2.2 A description of TDM Header items and values is provided in table 3-2, which
specifies for each item:
– the keyword to be used;
– a short description of the item;
– examples of allowed values; and
– whether the item is obligatory or not obligatory.
3.2.3 Only those keywords shown in table 3-2 shall be used in a TDM Header. The order of
occurrence of the obligatory and optional KVN assignments shall be fixed as shown in table 3-2.
Table 3-2: TDM Header
Keyword Description Examples Obligatory
CCSDS_TDM_VERS
Format version in the form of ‘x.y’, 0.12  (for testing) Yes

where ‘y’ shall be incremented for
1.0
corrections and minor changes, and

‘x’ shall be incremented for major

changes.
COMMENT
See 4.5. COMMENT This is a comment No
CREATION_DATE
Data creation date/time in UTC. Yes
2001-11-06T11:17:33
For format specification, see 4.3.9.
2002-204T15:56:23.4
2006-001T00:00:00Z
ORIGINATOR
Creating agency. Value should be CNES, ESOC, GSFC, GSOC, Yes
specified in the ICD. JPL, JAXA, etc.
3.2.4 Each line in the TDM Header, with the exception of COMMENTs, shall have the
following generic format:
keyword = value
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CCSDS RECOMMENDED STANDARD FOR TRACKING DATA MESSAGE
3.2.5 The TDM Header shall provide a CCSDS Tracking Data Message version number
that identifies the format version; this is included to anticipate future changes and to provide
the ability to extend the standard with no disruption to existing users. The version keyword is
CCSDS_TDM_VERS and the value shall have the form of x.y where y is incremented for
corrections and minor changes, and x is incremented for major changes. Version 1.0 shall be
reserved for the initial version accepted by the CCSDS as an official Recommended Standard
(‘Blue Book’). Interagency testing of TDMs shall be conducted using version numbers less
than 1.0 (e.g., ‘0.y’). Specific TDM versions that will be exchanged between agencies
should be documented via the ICD.
3.2.6 The TDM Header shall include the CREATION_DATE keyword with the value set to
the Coordinated Universal Time (UTC) when the data was created (file creation time if in file
format, or first data point in stream), as specified in reference [3] (ASCII Time Code A or B).
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CCSDS RECOMMENDED STANDARD FOR TRACKING DATA MESSAGE
3.3 TDM METADATA
3.3.1 GENERAL
3.3.1.1 The TDM shall include at least one Metadata Section that contains configuration
details (metadata) applicable to the Data Section in the same TDM Segment. The
information in the Metadata Section aligns with the tracking data to provide descriptive
information (typically, the metadata is the type of information that does not change
frequently during a tracking session).
3.3.1.2 Each line in the TDM Metadata Section, with the exception of COMMENTs, shall
have the following generic format:
keyword = value
3.3.1.3 A single TDM Metadata Section shall precede each Data Section.
3.3.1.4 When there are changes in the values assigned to any of the keywords in the
Metadata Section, a new Segment must be started (e.g., mode change from one-way to two-
way tracking).
3.3.1.5 The first and last lines of a TDM Metadata Section shall consist of the
META_START and META_STOP keywords, respectively. These keywords are used to
facilitate parsing.
3.3.1.6 Table 3-3 specifies for each Metadata item:
– the keyword to be used;
– a short description of the item;
– a list of required values or examples of allowed values; and
– whether the item is obligatory or not obligatory.
The column marked ‘N/E’ will contain an ‘N’ if the column marked ‘Normative Values /
Examples’ contains normative values, and will contain an ‘E’ if the column contains example
values that are non-normative. For normative values, a fully enumerated set of values may
be provided, or the contents of table 3-3 may be a sample of values that are fully enumerated
in an annex. In this latter case, the necessary annex is identified.
3.3.1.7 Only those keywords shown in table 3-3 shall be used in a TDM Metadata Section.
Obligatory items shall appear in every TDM Metadata Section. Items that are not obligatory
may or may not appear in any given TDM Metadata Section, at the discretion of the data
producer, based on the requirements of the data and its intended application (see annex G for
a TDM Summary Sheet that illustrates the relationships between data types and metadata).
For most metadata keywords there is no default value; where there is a default value, it is
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CCSDS RECOMMENDED STANDARD FOR TRACKING DATA MESSAGE
specified at the end of the ‘Description’ section for the given keyword. If a keyword is not
present in a TDM, and a default value is defined, the default shall be assumed.
3.3.1.8 The order of occurrence of the obligatory and optional KVN assignments shall be
fixed as shown in table 3-3.
3.3.1.9 The Metadata Section shall describe the participants in a tracking session using the
keyword ‘PARTICIPANT_n’. There may be several participants associated with a tracking
data session (the number of participants is always greater than or equal to one, and generally
greater than or equal to two). The ‘n’ in the keyword is an indexer. The indexer shall not be
the same for any two participants in a given Metadata Section.
3.3.1.10 The value associated with any given PARTICIPANT_n keyword may be a ground
track
...