SIST EN ISO 6709:2023
(Main)Standard representation of geographic point location by coordinates (ISO 6709:2022)
Standard representation of geographic point location by coordinates (ISO 6709:2022)
This document specifies the representation of latitude and longitude and optionally height or depth compatible with previous editions of ISO 6709.
This document also supports the representations of other coordinate types and time that can be associated with those coordinates as defined through one or more coordinate reference systems (CRS).
This document describes a text string of coordinates, suitable for electronic data exchange, for one point, including reference system identification to ensure that the coordinates unambiguously represent the position of that point. Files containing multiple points with a single common reference system identification are out of scope. This document also describes a simpler text string structure for coordinate representation of a point location that is more suitable for human readability.
Standarddarstellung für geographische Punkte durch Koordinaten (ISO 6709:2022)
Représentation normalisée de la localisation des points géographiques par coordonnées (ISO 6709:2022)
Le présent document spécifie la représentation de la latitude et la longitude, et, facultativement, de la hauteur ou de la profondeur compatible avec les versions précédentes de l'ISO 6709.
Le présent document prend également en charge les représentations d'autres types de coordonnées et de temps qui peuvent être associées à ces coordonnées, telles que définies par un ou plusieurs systèmes de référence de coordonnées (CRS, Coordinate Reference System).
Le présent document décrit une chaîne de texte de coordonnées, adaptée à l'échange de données électroniques, pour un point comprenant une identification de système de référence afin d'assurer que les coordonnées représentent la position de ce point sans ambiguïté. Les fichiers contenant plusieurs points avec une identification de système de référence commune unique n'entrent pas dans le domaine d'application. Le présent document décrit également une structure de chaîne de texte plus simple pour la représentation des coordonnées d'une localisation de point plus adaptée à la lisibilité humaine.
Standardna predstavitev geografske točkovne lokacije s koordinatami (ISO 6709:2022)
Ta dokument določa predstavitev zemljepisne širine in dolžine ter po izbiri višine ali globine, združljive s prejšnjimi izdajami standarda ISO 6709.
Dokument podpira tudi predstavitve drugih vrst koordinat in časa, ki jih je mogoče povezati s temi koordinatami, kot so opredeljene z enim ali več koordinatnimi referenčnimi sistemi (CRS).
Dokument opisuje besedilni niz koordinat, primeren za elektronsko izmenjavo podatkov, za eno točko, vključno z identifikacijo referenčnega sistema, ki zagotavlja, da koordinate nedvoumno predstavljajo položaj te točke. Datoteke, ki vsebujejo več točk z enotno identifikacijo skupnega referenčnega sistema, so zunaj področja uporabe dokumenta. Dokument opisuje tudi preprostejšo strukturo besedilnega niza za koordinatno predstavitev lokacije točke, ki je primernejša za človekovo berljivost.
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
01-januar-2023
Nadomešča:
SIST EN ISO 6709:2009
Standardna predstavitev geografske točkovne lokacije s koordinatami (ISO
6709:2022)
Standard representation of geographic point location by coordinates (ISO 6709:2022)
Standarddarstellung für geographische Punkte durch Koordinaten (ISO 6709:2022)
Représentation normalisée de la localisation des points géographiques par coordonnées
(ISO 6709:2022)
Ta slovenski standard je istoveten z: EN ISO 6709:2022
ICS:
07.040 Astronomija. Geodezija. Astronomy. Geodesy.
Geografija Geography
35.240.70 Uporabniške rešitve IT v IT applications in science
znanosti
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EN ISO 6709
EUROPEAN STANDARD
NORME EUROPÉENNE
October 2022
EUROPÄISCHE NORM
ICS 35.240.70 Supersedes EN ISO 6709:2009
English Version
Standard representation of geographic point location by
coordinates (ISO 6709:2022)
Représentation normalisée de la localisation des points Standarddarstellung für geographische Punkte durch
géographiques par coordonnées (ISO 6709:2022) Koordinaten (ISO 6709:2022)
This European Standard was approved by CEN on 5 July 2021.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2022 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 6709:2022 E
worldwide for CEN national Members.
Contents Page
European foreword . 3
European foreword
This document (EN ISO 6709:2022) has been prepared by Technical Committee ISO/TC 211
"Geographic information/Geomatics" in collaboration with Technical Committee CEN/TC 287
“Geographic Information” the secretariat of which is held by BSI.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by April 2023, and conflicting national standards shall be
withdrawn at the latest by April 2023.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 6709:2009.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the
United Kingdom.
Endorsement notice
The text of ISO 6709:2022 has been approved by CEN as EN ISO 6709:2022 without any modification.
INTERNATIONAL ISO
STANDARD 6709
Third edition
2022-09
Standard representation of geographic
point location by coordinates
Représentation normalisée de la localisation des points
géographiques par coordonnées
Reference number
ISO 6709:2022(E)
ISO 6709:2022(E)
© ISO 2022
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
ISO 6709:2022(E)
Contents Page
Foreword .iv
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Abbreviated terms and character code notations . 4
4.1 Abbreviated terms . 4
4.2 Character code notations . 5
5 Conformance . 5
6 Geographic point location (GPL) representation. 5
6.1 Overview . 5
6.2 Component representation . 6
6.3 Coordinate tuple. 6
6.4 Character string delimiters and terminator notation . 7
6.5 CRS identifier structure . 8
6.6 Text string representation . 10
6.6.1 Background . 10
6.6.2 Formatting rules for angular measures . 10
6.6.3 Component structure .12
7 Human-readable GPL representation .16
7.1 Overview of human-readable GPL representation . 16
7.2 General requirements of human-readable GPL representation . 16
7.3 Formatted examples of human-readable text strings . 18
Annex A (normative) Conformance and abstract test suite .20
Annex B (normative) Backwards compatible representation of geographic point location .23
Annex C (informative) Uniqueness of latitude and longitude coordinates .29
Annex D (informative) Latitude and longitude resolution.30
Annex E (informative) Changes compared to ISO 6709:2008 .31
Annex F (normative) Character encodings .33
Bibliography .35
iii
ISO 6709:2022(E)
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.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/
iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 211, Geographic information/Geomatics,
in collaboration with the European Committee for Standardization (CEN) Technical Committee CEN/TC
287, Geographic Information, in accordance with the Agreement on technical cooperation between ISO
and CEN (Vienna Agreement).
This third edition cancels and replaces the second edition (ISO 6709:2008), which has been technically
revised. It also incorporates the Technical Corrigendum ISO 6709:2008/Cor. 1:2009.
The main changes are as follows:
— Harmonization with other recently revised ISO/TC 211 International Standards;
— Clarification of normative requirements to maintain rigid backwards compatibility when required;
— Correction of the issues contained in the Technical Corrigendum ISO 6709:2008/Cor. 1:2009;
— Correction of annexes that contained normative requirements but were labelled as informative;
— Deletion of annexes and concepts which have changed and were no longer suitable for the revised
edition;
— Correction of instances where European numeric formatting conventions were incorrectly inserted.
These conventions will no longer be recommended;
— Clarification of editorial issues.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
In accordance with the ISO/IEC Directives, Part 2, 2018, Rules for the structure and drafting of
International Standards, in International Standards the decimal sign is a comma on the line. However,
the General Conference on Weights and Measures (Conférence Générale des Poids et Mesures) at its
meeting in 2003 passed unanimously the following resolution:
iv
ISO 6709:2022(E)
“The decimal marker shall be either a point on the line or a comma on the line.”
In practice, the choice between these alternatives depends on customary use in the language concerned.
In the technical areas of geodesy and geographic information it is customary for the decimal point
always to be used, for all languages. That practice is used throughout this document.
v
ISO 6709:2022(E)
Introduction
Geographic point location (GPL) is the description of a well-defined geographic place using a single
coordinate tuple. Efficient interchange of GPL data requires formats which are universally interpretable
and which allow the identification of points on, above and below the Earth’s surface. Users in various
disciplines have different requirements. This is exemplified by the use of degrees and decimal degrees,
as well as the traditional degrees, minutes and seconds, for recording latitude and longitude. User
applications can also require various levels of precision and can use latitude and longitude without
height.
ISO 6709:1983 defined a specific format representation of latitude and longitude, and optionally
altitude.
ISO 6709:2008 revised the format representation of the 1983 edition by:
— adding the ability to identify the coordinate reference system (CRS) to which coordinates are
referenced, without which location is ambiguous, and
— expanding the use of altitude to allow for any ellipsoidal or gravity-related height or depth.
Since the first edition of this document in 1983, the field of geodesy has undergone significant
technological advances, along with the continued development of other related geodesy and geomatics
standards.
The aim of this edition is to address these new advances and standards and to revise the coordinate
string suitable for digital representation (Clause 6) while continuing to support the requirements of the
previous edition (Annex B).
Clause 7 defines a simpler structure for the unambiguous representation of GPL in a human-readable
format.
In addition, a series of annexes are provided with the following content:
— Annex A (normative) defines the abstract test suite used for conformance testing;
— Annex B (normative) defines the representation of latitude and longitude coordinates that maintain
backwards compatibility with ISO 6709:2008;
— Annex C (informative) presents a description and examples of how the position of coordinates can
appear ambiguous without the use of a CRS;
— Annex D (informative) presents a table of mathematical precision values of resolution for latitude
and longitude;
— Annex E (informative) describes the changes in this document compared to the previous edition of
ISO 6709;
— Annex F (normative) specifies encodings for character strings and delimiters required in this
document.
The following options are highlighted to users of this document:
a) For all cases where backwards compatibility is not required, this document recommends using
the methods and rules specified in Clause 6, GPL representation, or Clause 7, human-readable GPL
representation;
b) However, in systems and environments where backwards compatibility with ISO 6709:2008 is
required, the methods and rules specified in Annex B can be used.
In addition, when using Annex B, it is recommended that suitable and comprehensive ancillary
documentation, not defined within this document or in previous editions of this document, be
vi
ISO 6709:2022(E)
prepared and accompany all instances of geographic point location text strings and human-readable
representations claiming backwards compatibility.
The use of this document:
— establishes an expanded point representation string format supporting the current concepts and
standards of geodesy and geographic information;
— when required, continues to support the needs of established user communities by maintaining
backwards compatibility with the previous edition of this document (ISO 6709:2008);
— reduces the cost of interchange of data;
— reduces the delay in converting non-standard coding structures in preparation for interchange by
providing advance knowledge of the standard interchange format; and
— provides flexible support for geographic point representation.
vii
INTERNATIONAL STANDARD ISO 6709:2022(E)
Standard representation of geographic point location by
coordinates
1 Scope
This document specifies the representation of latitude and longitude and optionally height or depth
compatible with previous editions of ISO 6709.
This document also supports the representations of other coordinate types and time that can be
associated with those coordinates as defined through one or more coordinate reference systems (CRS).
This document describes a text string of coordinates, suitable for electronic data exchange, for
one point, including reference system identification to ensure that the coordinates unambiguously
represent the position of that point. Files containing multiple points with a single common reference
system identification are out of scope. This document also describes a simpler text string structure for
coordinate representation of a point location that is more suitable for human readability.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 8601-1, Date and time — Representations for information interchange — Part 1: Basic rules
ISO 8601-2, Date and time — Representations for information interchange — Part 2: Extensions
ISO/IEC 10646:2020, Information technology — Universal coded character set (UCS)
ISO 19111, Geographic information — Referencing by coordinates
ISO 19162, Geographic information — Well-known text representation of coordinate reference systems
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
accuracy
closeness of agreement between a test result or measurement result and the true value
[SOURCE: ISO 3534-2:2006, 3.1.1, modified — Notes to entry have been removed.]
3.2
altitude
height where the chosen reference surface is mean sea level
ISO 6709:2022(E)
3.3
compound coordinate reference system
coordinate reference system using at least two independent coordinate reference systems
Note 1 to entry: Coordinate reference systems are independent of each other if coordinate values in one cannot
be converted or transformed into coordinate values in the other.
[SOURCE: ISO 19111:2019, 3.1.3]
3.4
coordinate
one of a sequence of numbers designating the position of a point
Note 1 to entry: In a spatial coordinate reference system, the coordinate numbers are qualified by units.
[SOURCE: ISO 19111:2019, 3.1.5]
3.5
coordinate reference system
coordinate system that is related to an object by a datum
Note 1 to entry: Geodetic and vertical datums are referred to as reference frames.
Note 2 to entry: For geodetic and vertical reference frames, the object will be the Earth. In planetary applications,
geodetic and vertical reference frames may be applied to other celestial bodies.
[SOURCE: ISO 19111:2019, 3.1.9]
3.6
coordinate set
collection of coordinate tuples referenced to the same coordinate reference system and if that
coordinate reference system is dynamic also to the same coordinate epoch
[SOURCE: ISO 19111:2019, 3.1.10]
3.7
coordinate system
set of mathematical rules for specifying how coordinates are to be assigned to points
[SOURCE: ISO 19111:2019, 3.1.11]
3.8
coordinate tuple
tuple composed of coordinates
Note 1 to entry: The number of coordinates in the coordinate tuple equals the dimension of the coordinate
system; the order of coordinates in the coordinate tuple is identical to the order of the axes of the coordinate
system.
[SOURCE: ISO 19111:2019, 3.1.13]
3.9
datum
reference frame
parameter or set of parameters that realize the position of the origin, the scale, and the orientation of a
coordinate system
[SOURCE: ISO 19111:2019, 3.1.15]
ISO 6709:2022(E)
3.10
depth
distance of a point from a chosen vertical reference surface downward along a line that is perpendicular
to that surface
Note 1 to entry: The line direction may be straight or be dependent on the Earth's gravity field or other physical
phenomena.
Note 2 to entry: A depth above the vertical reference surface will have a negative value.
[SOURCE: ISO 19111:2019, 3.1.17]
3.11
ellipsoidal height
geodetic height
h
distance of a point from the reference ellipsoid along the perpendicular from the reference ellipsoid to
this point, positive if upwards or outside of the reference ellipsoid
Note 1 to entry: Only used as part of a three-dimensional ellipsoidal coordinate system or as part of a three-
dimensional Cartesian coordinate system in a three-dimensional projected coordinate reference system, but
never on its own.
[SOURCE: ISO 19111:2019, 3.1.24]
3.12
geographic point location
well defined geographic place described by one coordinate tuple
[SOURCE: ISO 19145:2013, 4.1.11]
3.13
geographic point location representation
syntactic description of a geographic point location in a well known format
[SOURCE: ISO 19145:2013, 4.1.12]
3.14
gravity-related height
H
height that is dependent on the Earth’s gravity field
Note 1 to entry: This refers to, amongst others, orthometric height and Normal height, which are both
approximations of the distance of a point above the mean sea level, but also may include Normal-orthometric
heights, dynamic heights or geopotential numbers.
Note 2 to entry: The distance from the reference surface may follow a curved line, not necessarily straight, as it is
influenced by the direction of gravity.
[SOURCE: ISO 19111:2019, 3.1.37]
3.15
height
distance of a point from a chosen reference surface positive upward along a line perpendicular to that
surface
Note 1 to entry: A height below the reference surface will have a negative value.
Note 2 to entry: Generalisation of ellipsoidal height (h) and gravity-related height (H).
[SOURCE: ISO 19111:2019, 3.1.38]
ISO 6709:2022(E)
3.16
measurement precision
precision
closeness of agreement between indications or measured quantity values obtained by replicate
measurements on the same or similar objects under specified conditions
Note 1 to entry: Measurement precision is usually expressed numerically by measures of imprecision, such as
standard deviation, variance, or coefficient of variation under the specified conditions of measurement.
Note 2 to entry: The "specified conditions" can be, for example, repeatability conditions of measurement,
intermediate precision conditions of measurement, or reproducibility conditions of measurement (see
ISO 5725-1:1994).
Note 3 to entry: Measurement precision is used to define measurement repeatability, intermediate measurement
precision, and measurement reproducibility.
Note 4 to entry: Sometimes "measurement precision" is erroneously used to mean measurement accuracy.
[SOURCE: ISO/IEC Guide 99:2007, 2.15]
3.17
metadata
information about a resource
[SOURCE: ISO 19115-1:2014, 4.10]
3.18
resolution (of a coordinate)
unit associated with the least significant digit of a coordinate
Note 1 to entry: Coordinate resolution may have linear or angular units depending on the characteristics of the
coordinate system.
3.19
sexagesimal degree
angle represented by a sequence of values in degrees, minutes, and seconds
Note 1 to entry: In the case of latitude or longitude, it may also include a character indicating hemisphere.
EXAMPLE 50.0795725 decimal degrees is represented as 50°04'46.461"
3.20
tuple
ordered list of values
Note 1 to entry: The number of values in a tuple is immutable.
[SOURCE: ISO 19136-1:2020, 3.1.60]
4 Abbreviated terms and character code notations
4.1 Abbreviated terms
CRS coordinate reference system
CRScsd coordinate reference system character string delimiter
EPSG EPSG geodetic parameter dataset
GML Geography Markup Language
ISO 6709:2022(E)
GPL geographic point location
HTML HyperText Markup Language
ISOGR ISO Geodetic Registry
JSON JavaScript Object Notation
lat latitude
lon longitude
OGC Open Geospatial Consortium
UCS Universal Coded Character Set
URL Uniform Resource Locator
WKT well-known text
XML eXtensible Markup Language
4.2 Character code notations
Character string delimiters required in this document are represented in accordance with notation
from ISO/IEC 10646. Character names and code points are specified in Annex F, Table F.1.
5 Conformance
To conform to this document, representations of GPL shall satisfy the conditions specified in the
abstract test suite (Annex A).
6 Geographic point location (GPL) representation
6.1 Overview
This edition of ISO 6709 revises and expands the representation of geographic point location (GPL),
while maintaining an option (Annex B) for backwards compatibility with the previous edition
(ISO 6709:2008).
ISO 19111 defines the elements required to describe a CRS. A coordinate tuple represents a location
unambiguously only if the CRS to which it is referenced is identified and if that CRS is dynamic the
epoch of the coordinates is also identified. Without this identification, uncertainty in position can result
in the location being as much as several hundred metres distant (see Annex C).
In this document, CRS identifiers shall accompany all GPL representations. Identification may be
through:
— a complete URL notation [6.5 a)],
— an abbreviated notation [6.5 b)] or
— a complete CRS definition as specified in ISO 19111, [6.5 c)].
ISO 19111 specifies several CRS types, of which the following are supported in this document. Any one,
or a combination of these, shall accompany all GPL representations:
— geodetic CRS — three-dimensional,
ISO 6709:2022(E)
— geographic CRS — two-dimensional or three-dimensional,
— projected CRS — two-dimensional, or sometimes three-dimensional,
— engineering CRS — two-dimensional, or sometimes one-dimensional or three-dimensional,
— parametric CRS — one-dimensional, with normally vertical orientation,
— vertical CRS — one-dimensional,
— temporal CRS — one-dimensional, and
— compound CRS.
NOTE For detailed information about each of these CRS types users can consult ISO 19111.
The text string representation format defined in 6.6 is used for single GPL instances. However, in
practice, GPL instances with uniform representation formats are commonly grouped into coordinate
sets that often provide a single CRS identification for the complete coordinate set. This single
identification does not adhere to the specified representation requirements defined by this document.
These types of coordinate sets are commonly formatted as files on digital storage, or structures in
computer memory.
This document does not specify the format of these coordinate sets, and when coordinate sets are used,
this document recommends that users provide suitable, clear and persistent documentation detailing
the CRS identifiers of all elements in the GPL representation and character encoding used.
6.2 Component representation
This document specifies the representation of GPLs using the descriptive concept of a component. Each
component is comprised of three required elements:
— a coordinate tuple (6.3),
— a character string delimiter (6.4), and
— a CRS identifier (6.5).
A series of components can then be combined to define a GPL representation.
The order of the components occurring in a GPL representation text string is not defined by this
document and therefore enables any ordering of the components according to user or system
requirements, provided a valid CRS identifier element accompanies each component. Parsing and
identification of each component is possible by examining the character string delimiter.
The order and units of the coordinate tuples in each component are defined by the specific CRS.
However, in a compound CRS, the CRS not only defines the required coordinate tuples but also the order
of the components within the compound group.
6.3 Coordinate tuple
A coordinate tuple is an ordered list of values composed of coordinates. The coordinates within a
coordinate tuple are mutually independent. The number of coordinates in a tuple is equal to the
dimension of the coordinate system and the order of the coordinates in the coordinate tuple is identical
to the order of the axes of the coordinate system. The order and units of the coordinate tuple are
specified in the CRS definition associated with the component.
ISO 6709:2022(E)
6.4 Character string delimiters and terminator notation
To differentiate GPL strings specified in this document from those represented using formats defined
in the previous edition (ISO 6709:2008, Annex E.2), a new CRS character string delimiter (CRScsd) is
defined.
For specific formatting requirements shown in this document, users should refer to the character
encodings defined in Table F.1.
NOTE 1 Within this document, the notation CRScsd refers to a general CRS character string delimiter reference.
The format of the new CRScsd is composed of:
— the uppercase letters "CRS", immediately followed by;
— a single digit, either a 1, 2, 3 or 4, immediately followed by;
— a lowercase "d".
EXAMPLE 1 CRS2d is an example of a well-formed CRScsd.
The two characters immediately following the "CRS" together represent the dimension of the CRS and
are referred to as the suffix of the CRS character string delimiter.
The following CRScsd strings represent the CRS types supported by this document:
a) CRS1d: one-dimensional spatial or temporal CRS.
EXAMPLE 2 Height, depth, pressure and time are examples of one-dimensional coordinate tuple
elements.
b) CRS2d: two-dimensional single spatial CRS or two-dimensional compound CRS.
EXAMPLE 3 Lat/Lon, X/Y, Easting/Northing and polar coordinates are examples of two-dimensional
coordinate tuple elements. A two-dimensional compound CRS identifier can define elements such as height
and time.
c) CRS3d: three-dimensional single spatial CRS or three-dimensional compound CRS.
EXAMPLE 4 Lat/Lon/height, X/Y/Z and spherical coordinates are examples of three-dimensional
coordinate tuple elements. A three-dimensional compound CRS identifier can define elements such as
horizontal (Lat/Lon) plus time, where time can be the epoch of the coordinates.
d) CRS4d: four-dimensional single spatial CRS or four-dimensional compound CRS.
EXAMPLE 5 Lat/Lon/height/time and X/Y/Z/time are examples of four-dimensional coordinate tuple
elements. A four-dimensional compound CRS identifier can define elements, such as X/Y/Z and time, where
time can be an epoch of the coordinates.
Additionally, in each component of a GPL representation string, the following characters shall also act
as delimiters:
e) the plus sign or minus sign [ +/− ] of the value acts as a delimiter between the coordinates of the
tuple.
f) a commercial at [ @ ] is used as a prefix delimiter of a coordinate epoch (ISO 19111:2019, B.4.3). The
epoch refers to the coordinates and does not belong to the CRS and therefore does not modify the
CRS definition in any way. When a coordinate epoch is used, the epoch prefix "@" and epoch value
shall immediately precede the CRScsd and there shall be no spaces between the end digits of the
coordinate and the epoch prefix.
g) curly brackets [ { } ] are used to enclose a date/time string, in accordance with ISO 8601-1 or
ISO 8601-2. The date/time string enclosed between curly brackets, without leading or trailing
ISO 6709:2022(E)
spaces, immediately precedes a CRS1d character string delimiter following the rules for CRS
identifier structure (6.5).
h) angle brackets [ < > ] are used to enclose the CRS identifier and immediately follow the CRScsd
according to the rules for CRS identifier structure (6.5).
NOTE 2 While the character names defined in Table F.1 are "LESS-THAN SIGN" and "GREATER-THAN
SIGN", this document follows customary notation used in other ISO/TC 211 documents and collectively
refers to these characters as "angle brackets".
i) a solidus [ / ] shall act as the terminator character and any GPL string shall always be terminated.
6.5 CRS identifier structure
Three methods exist for representing the CRS identifier structure. The complete URL notation [6.5 a)]
provides an unambiguous reference to an authoritative CRS identifier, which is available in a registry
and is suitable for implementation purposes, whereas the abbreviated notation [6.5 b)] uses various
shortened descriptive references that represent a CRS identifier, but do not necessarily return an
unambiguous reference to an authoritative CRS and are less useful for implementation purposes. The
complete CRS definition as specified in ISO 19111 [6.5 c)] is used when the required CRS is not available
in a registry, or when it is desirable to give the definition in full, despite there being a registry entry.
Any CRS identifier shall be enclosed within angle brackets < > immediately following the CRScsd.
NOTE 1 In the following structure definitions, the CRScsd, angle bracket delimiters and terminator character
are shown in monospace bold regular type. The examples shown in this subclause are fragments of GPL
representation strings and are designated as such by the "…" ellipsis at the start of each example.
The structure of the CRS identifier is defined for the following cases:
a) complete URL notation:
CRScsd/
where registryURL is a well-formed URL, without leading or trailing spaces, and returns the CRS
identifier either as a human interface endpoint (e.g. HTML) or as service endpoint (e.g. XML, GML,
WKT, JSON, etc.).
NOTE 2 The endpoint preference is based on the requirements of the user.
EXAMPLE 1
…CRS3d/
An HTML endpoint from the ISO Geodetic Registry (ISOGR) defining NAD 83 (HARN) CORRECTED
– LatLonEHt, ID 204.
EXAMPLE 2
…CRS3d/
An XML/GML endpoint from the EPSG Registry, defining geographic 3D WGS84 CRS - EPSG code
4979.
EXAMPLE 3
…CRS3d/
An XML/GML endpoint from the IGNF (Institut Géographique National France) Registry defining a
geocentric CRS representing cartesiennes geocentriques, ID RGF93.
ISO 6709:2022(E)
b) abbreviated notation:
CRScsd/
where registry identifier (registryID) is a text string, without leading or trailing spaces, immediately
followed by a single colon (:) then immediately followed by the CRS identifier (CRS-ID) from the
registry.
Abbreviated notation can be:
— an authoritative identifier from a registry (Example 4),
— a "working identifier alias", used within a specific organization or domain, where the description
and parameters of the CRS identifier are clearly understood by the members of the organization or
domain (Example 5), or
— in the absence of an actual working registry, an authoritative source and document identifier can be
provided (Example 6).
EXAMPLE 4
…CRS2d/
Abbreviated notation of EPSG ID 5345, representing a projected 2D POSGAR 2007/Argentina Zone
3 CRS, defined online by: https:// api .epsg .org/ def/ crs/ EPSG/ 0/ 5345/ gml or https:// epsg .org/ crs
_5345/ index .html
EXAMPLE 5
…CRS3d/
To a specific group, the working notation of "OS -CRS: OSGB36 NG-ODN" is unambiguous within their
group or organization. However, it is also identical to the CRS identifier EPSG 7405 as defined by:
https:// api .epsg .org/ def/ crs/ EPSG/ 0/ 7405/ gml or https:// api .epsg .org/ def/ crs/ EPSG/ 0/ 7405/ wkt
NOTE 3 This document recommends that instances of "working" identifiers be clearly documented.
EXAMPLE 6
…CRS1d/
This example shows an ISO document (ISO 8601-2:2019) used as a type of offline CRS registry. In
the example, an ISO 8601-2 date/time string format is used and a specific document is required to
interpret the format. Therefore, an abbreviated form of the International Standard name has been
placed into the CRS identifier.
NOTE 4 As only one colon is defined in 6.5 b), the typical "colon notation" (document _number: publication
_date) used in the ISO document title (8601-2:2019) has been replaced in Example 6 with a space.
c) complete CRS definition as specified in ISO 19111:
CRScsd/
where ISO_19111_complete_CRS_definition is represented using a WKT formatted string
(ISO 19162), having no leading or trailing spaces, and surrounded by a pair of angle brackets (< >).
A complete CRS definition can be:
— used when online or official registry entries are not available,
— used when modifications to specific parameters are required (Example 7).
The full description is generally used only when reference to a description in a registry is not possible.
ISO 6709:2022(E)
The full description shall be given through well-known text (WKT), conformant with ISO 19162.
EXAMPLE 7
...CRS2d
BASEGEOGCRS["JGD2011",DATUM["Japanese Geodetic Datum 2011",
ELLIPSOID["GRS 1980",6378137,298.257222101,LENGTHUNIT
["metre",1.0]]]],CONVERSION["My map projection",METHOD["Transverse
Mercator",ID["EPSG",9807]],PARAMETER["Latitude of natural
origin",0,ANGLEUNIT["degree",0.01745329252]],PARAMETER
["Longitude of natural origin",144,ANGLEUNIT["degree",0.01745329252]],
PARAMETER["Scale factor at natural origin",0.9996,
SCALEUNIT["unity",1.0]],PARAMETER["False easting",500000,
LENGTHUNIT["metre",1.0]],PARAMETER["False northing",2000000,
LENGTHUNIT["metre",1.0]]],CS[cartesian,2],AXIS["easting
(E)",east,ORDER[1]],AXIS["northing (N)",north,ORDER[2]],
LENGTHUNIT["metre",1.0]]>/
This example shows a complete CRS definition, as specified by ISO 19111, in the form of a WKT
string for a two-dimensional projected CRS using a user-defined map projection not found in a
registry (the False northing is modified).
NOTE 5 When necessary, examples in this document use carriage returns to wrap the lines for readability and
are not part of the specification.
6.6 Text string representation
6.6.1 Background
The GPL text string representation, defined in previous editions of this document, has been widely
implemented in many information systems because of its simple representation, ease of understanding
and relatively modest memory storage requirements.
While the GPL text string representation specified in this document maintains a similar approach to
that of previous editions in terms of simplicity, understanding and storage requirements, the overall
formatting rules defined in this document are closely aligned with the CRS identifier of each component.
To structure GPL text string representations conforming to this document, the rules in 6.6.2 and 6.6.3
shall apply.
6.6.2 Formatting rules for angular measures
6.6.2.1 Background
The required CRS identifier (6.5) in each component is used to interpret the format and values of the
coordinate tuples within the specific component. Therefore, the order and units of measure (UoM), or
simply, "units" of the coordinates, shall match the order and units defined in the CRS identifier. If the
order and/or units are incompatible or different, the GPL representation is considered invalid and the
unambiguous interpretation of the text string will fail.
Within a registry, it is expected that the CRS identifiers contain complete definitions for all attributes.
However, some definitions allow the supplier to define specific representations, such as the format of
latitude and longitude coordinates, where the units ar
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