SIST EN ISO 19168-2:2023
(Main)Geographic information - Geospatial API for features - Part 2: Coordinate Reference Systems by Reference (ISO 19168-2:2022)
Geographic information - Geospatial API for features - Part 2: Coordinate Reference Systems by Reference (ISO 19168-2:2022)
This document specifies an extension to the Geospatial API for Features — Part 1: Core standard that
defines the behaviour of a server that supports the ability to present geometry valued properties in a
response document in one from a list of supported Coordinates Reference Systems (CRS).
Each supported CRS is specified by reference using a uniform resource identifier (URI).
This document specifies:
— how, for each offered feature collection, a server advertises the list of supported CRS identifiers;
— how the coordinates of geometry valued feature properties can be accessed in one of the supported
CRSs;
— how features can be accessed from the server using a bounding box specified in one of the supported
CRSs; and
— how a server can declare the CRS used to present feature resources.
Geoinformation - Raumbezogene API für Features - Teil 2: Koordinatenreferenzsystem durch Referenz (ISO 19168-2:2022)
Information géographique - API géospatiale pour les entités - Partie 2: Systèmes de coordonnées de référence par référence (ISO 19168-2:2022)
Le présent document spécifie une extension à la norme «API géospatiale pour les entités — Partie 1: Profil minimal» qui définit le comportement d'un serveur qui est en capacité de présenter des propriétés associées à une valeur géométrique dans un document de réponse dans une liste de Systèmes de coordonnées de référence (CRS) pris en charge.
Chaque CRS pris en charge est spécifié par référence à l'aide d'un identifiant de ressource universel (URI).
Le présent document spécifie:
— comment, pour chaque collection d'entités proposée, un serveur publie la liste des identifiants de CRS pris en charge;
— comment les coordonnées des propriétés d'entités associées à une valeur géométrique peuvent être accessibles dans l'un des CRS pris en charge;
— comment les entités peuvent être accessibles depuis le serveur à l'aide d'un rectangle englobant spécifié dans l'un des CRS pris en charge; et
— comment un serveur peut déclarer le système de CRS utilisé pour présenter des ressources d'entités.
Geografske informacije - Geoprostorski API za funkcije - 2. del: Koordinatni referenčni sistemi po referenci (ISO 19168-2:2022)
Ta dokument je dodatek k standardu Geoprostorski API za funkcije - 1. del: Osrednji profil,
ki določa vedenje strežnika, ki podpira zmožnost predstavitve geometrijsko vrednotenih lastnosti
v odzivnem dokumentu na enem od seznamov podprtih koordinatnih referenčnih sistemov (CRS).
Vsak podprt CRS je določen na podlagi reference z uporabo enoličnega identifikatorja vira (URI).
Ta dokument določa:
– kako strežnik za vsako ponujeno zbirko funkcij objavi seznam podprtih identifikatorjev CRS;
– kako je mogoče dostopati do koordinat lastnosti elementov z geometrijskimi vrednostmi v enem od podprtih
CRS-jev;
– kako je mogoče dostopati do funkcij iz strežnika z uporabo omejevalnega polja, določenega v enem od podprtih
CRS-jev; in
– kako lahko strežnik navede CRS, ki se uporablja za predstavitev virov funkcij.
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN ISO 19168-2:2023
01-januar-2023
Geografske informacije - Geoprostorski API za funkcije - 2. del: Koordinatni
referenčni sistemi po referenci (ISO 19168-2:2022)
Geographic information - Geospatial API for features - Part 2: Coordinate Reference
Systems by Reference (ISO 19168-2:2022)
Geoinformation - Raumbezogene API für Features - Teil 2: Koordinatenreferenzsystem
durch Referenz (ISO 19168-2:2022)
Information géographique - API géospatiale pour les entités - Partie 2: Systèmes de
coordonnées de référence par référence (ISO 19168-2:2022)
Ta slovenski standard je istoveten z: EN ISO 19168-2:2022
ICS:
07.040 Astronomija. Geodezija. Astronomy. Geodesy.
Geografija Geography
35.240.70 Uporabniške rešitve IT v IT applications in science
znanosti
SIST EN ISO 19168-2:2023 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN ISO 19168-2:2023
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SIST EN ISO 19168-2:2023
EN ISO 19168-2
EUROPEAN STANDARD
NORME EUROPÉENNE
October 2022
EUROPÄISCHE NORM
ICS 35.240.70
English Version
Geographic information - Geospatial API for features - Part
2: Coordinate Reference Systems by Reference (ISO
19168-2:2022)
Information géographique - API géospatiale pour les Geoinformation - Raumbezogene API für Features -
entités - Partie 2: Systèmes de coordonnées de Teil 2: Koordinatenreferenzsystem durch Referenz
référence par référence (ISO 19168-2:2022) (ISO 19168-2:2022)
This European Standard was approved by CEN on 29 April 2022.
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 19168-2:2022 E
worldwide for CEN national Members.
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SIST EN ISO 19168-2:2023
EN ISO 19168-2:2022 (E)
Contents Page
European foreword . 3
2
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SIST EN ISO 19168-2:2023
EN ISO 19168-2:2022 (E)
European foreword
This document (EN ISO 19168-2:2022) 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.
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 19168-2:2022 has been approved by CEN as EN ISO 19168-2:2022 without any
modification.
3
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SIST EN ISO 19168-2:2023
INTERNATIONAL ISO
STANDARD 19168-2
First edition
2022-09
Geographic information – Geospatial
API for features —
Part 2:
Coordinate Reference Systems by
Reference
Information géographique — API géospatiale pour les entités —
Partie 2: Systèmes de coordonnées de référence par référence
Reference number
ISO 19168-2:2022(E)
© ISO 2022
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SIST EN ISO 19168-2:2023
ISO 19168-2:2022(E)
COPYRIGHT PROTECTED DOCUMENT
© 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
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SIST EN ISO 19168-2:2023
ISO 19168-2:2022(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Conformance . 2
5 Conventions and background.2
6 Requirements Class Coordinate Reference Systems by Reference . 3
6.1 Overview . 3
6.2 Discovery . 3
6.2.1 CRS identifier list . 3
6.2.2 Storage CRS . 4
6.2.3 Global list of CRS identifiers . 5
6.3 Query . 8
6.3.1 Parameter bbox-crs . 8
6.3.2 Parameter crs . 9
6.3.3 Output format considerations . 10
6.3.4 Coordinate reference system information independent of the feature
encoding . 11
Annex A (normative) Abstract Test Suite .12
Bibliography .16
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SIST EN ISO 19168-2:2023
ISO 19168-2:2022(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 (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 the Open Geospatial Consortium (as OGC API — Features — Part 2:
Coordinate Reference Systems by Reference) and drafted in accordance with its editorial rules. It was
assigned to Technical Committee ISO/TC 211, Geographic information/Geomatics, and adopted under
the “fast-track procedure”.
The main changes are as follows:
— addition of an Introduction;
— alignment of spellings with ISO spelling rules;
— renumbering and reordering of Clauses 2-4 in order to accommodate the fixed structure of ISO
documents;
— set texts introduced in Clauses 2 and 3;
A list of all parts in the ISO 19168 series can be found on the ISO website.
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.
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ISO 19168-2:2022(E)
Introduction
OGC API standards define modular API building blocks to spatially enable Web APIs in a consistent way.
The OpenAPI specification is used to define the API building blocks.
The OGC API family of standards is organized by resource type. This document extends the fundamental
API building blocks for interacting with features. The spatial data community uses the term 'feature'
for things in the real world that are of interest.
For those not familiar with the term 'feature,' the explanations on Spatial Things, Features and
[6]
Geometry in the W3C/OGC Spatial Data on the Web Best Practice document provide more detail.
OGC API Features provides API building blocks to create, modify and query features on the Web. OGC
API Features is comprised of multiple parts, each of them is a separate standard. This document extends
the core capabilities specified in OGC API — Features — Part 1: Core (ISO 19168-1) with the ability to
use coordinate reference system identifiers other than the defaults defined in the core.
By default, every API implementing this document will provide access to a single dataset. Rather than
sharing the data as a complete dataset, the OGC API Features standards offer direct, fine-grained access
to the data at the feature (object) level.
The API building blocks specified in this document are consistent with the architecture of the Web.
In particular, the API design is guided by the IETF HTTP/HTTPS RFCs, the W3C Data on the Web
Best Practices, the W3C/OGC Spatial Data on the Web Best Practices and the emerging OGC Web API
Guidelines. A particular example is the use of the concepts of datasets and dataset distributions as
defined in DCAT and used in schema.org.
A subset of the OGC API family of standards is expected to be published by ISO. For example, this
document is published by ISO as ISO 19168-2. To reflect that only a subset of the OGC API standards
will be published by ISO and to avoid using organization names in the titles of ISO standards, standards
from the "OGC API" series are published by ISO as "Geospatial API," i.e. the title of this document in OGC
is "OGC API — Features — Part 2: Coordinate Reference Systems by Reference" and the title in ISO is
"Geographic Information — Geospatial API for Features — Part 2: Coordinate Reference Systems by
Reference."
For simplicity, this document consistently uses:
— "OGC API" to refer to the family of standards for geospatial Web APIs that in ISO is published as
"Geospatial API;"
— "OGC API — Features" to refer to the multipart standard for features that in ISO is published as
ISO 19168 / "Geographic Information - Geospatial API for Features;"
— "OGC API — Features — Part 1: Core" to refer to the document that in ISO is published as ISO 19168-1
/ "Geographic Information - Geospatial API for Features - Part 1: Core."
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SIST EN ISO 19168-2:2023
INTERNATIONAL STANDARD ISO 19168-2:2022(E)
Geographic information – Geospatial API for features —
Part 2:
Coordinate Reference Systems by Reference
1 Scope
This document specifies an extension to the Geospatial API for Features — Part 1: Core standard that
defines the behaviour of a server that supports the ability to present geometry valued properties in a
response document in one from a list of supported Coordinates Reference Systems (CRS).
Each supported CRS is specified by reference using a uniform resource identifier (URI).
This document specifies:
— how, for each offered feature collection, a server advertises the list of supported CRS identifiers;
— how the coordinates of geometry valued feature properties can be accessed in one of the supported
CRSs;
— how features can be accessed from the server using a bounding box specified in one of the supported
CRSs; and
— how a server can declare the CRS used to present feature resources.
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 19168-1:2020, Geographic information — Geospatial API for features — Part 1: Core
3 Terms and definitions
For the purposes of this document, the terms and definition given in ISO19168-1 and the following
apply.
ISO and IEC maintain terminology 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/
NOTE The terms feature (3.4) and feature collection (3.5) and the acronym CRS (3.2) are duplicated here
from ISO 19168-1.
3.1
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]
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ISO 19168-2:2022(E)
3.2
coordinate reference system
CRS
coordinate system (3.3) 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 application,
geodetic and vertical reference frames may be applied to other celestial bodies.
[SOURCE: ISO 19111:2019, 3.1.9]
3.3
coordinate system
set of mathematical rules for specifying how coordinates (3.1) are to be assigned to points
[SOURCE: ISO 19111:2019, 3.1.11]
3.4
feature
abstraction of real world phenomena
Note 1 to entry: The explanations on Spatial Things, Features and Geometry in the W3C/OGC Spatial Data on the
[6]
Web Best Practice document provide more detail.
[SOURCE: ISO 19101-1:2014, 4.1.11, modified – Note 1 to entry has been added.]
3.5
feature collection
collection
set of features (3.4) from a dataset (ISO 19168-1, 3.1.1)
3.6
spatial feature collection
spatial collection
feature collection (3.5) that includes one or more features (3.4) that have properties whose value is a
geometry
[SOURCE: ISO 19168-1:2020, 3.1.4]
4 Conformance
This document defines one requirements class, Coordinate Reference Systems by Reference. The
standardization target is "Web APIs".
The URI of the associated conformance class is http:// www .opengis .net/ spec/ ogcapi -features -2/ 1 .0/
conf/ crs.
Conformance with this standard shall be checked using all the relevant tests specified in Annex A of
this document. The framework, concepts, and methodology for testing, and the criteria to be achieved
to claim conformance are specified in the OGC Compliance Testing Policies and Procedures and the OGC
Compliance Testing web site.
5 Conventions and background
See ISO 19168-1:2020, Clauses 5 and 6.
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6 Requirements Class Coordinate Reference Systems by Reference
6.1 Overview
Requirements Class
http:// www .opengis .net/ spec/ ogcapi -features -2/ 1 .0/ req/ crs
Target type Web API
Dependency OGC API - Features - Part 1: Core, Requirements Class 'core'
The OGC API — Features — Part 1: Core standard defines support for only two coordinate reference
systems:
— WGS 84 longitude, latitude;
— WGS 84 longitude, latitude, ellipsoidal height.
This extension defines the behaviour of a server that supports additional coordinate reference systems.
Requirement 1 /req/crs/crs-uri
Each CRS supported by a server shall be referenceable by a uniform resource identifier (i.e. a URI).
Recommendation 1 /rec/crs/crs-format-model
Servers that implement this extension should be able to recognize and generate CRS identifiers with the following
format model:
http://www.opengis.net/def/crs/authority/version/code
In this format model, the token {authority} is a placeholder for a value that designates to authority responsible
for the definition of this CRS. Typical values include "EPSG" and "OGC".
The token {version} is a placeholder for the specific version of the CRS definition or 0 for un-versioned CRS
definitions.
The token {code} is a placeholder for the authority’s code for the CRS.
For more information, see 6.2 in OGC Name Type Specification, Part 1.
Note that while the EPSG register itself is versioned, the registered items are not versioned and the
"version" is always "0" in URIs of the authority "EPSG".
6.2 Discovery
6.2.1 CRS identifier list
Requirement 2 /req/crs/fc-md-crs-list
A The crs property in the collection object of a spatial feature collection shall contain the
identifiers for the list of CRSs supported by the server for that collection.
B This list shall include the default(s) defined in OGC API - Features - Part 1: Core.
The list has to include the default CRS — that is the CRS used unless something else is explicitly
requested — is defined in ISO 19168-1, Geographic information — Geospatial API for features — Part 1:
Core as:
— http:// www .opengis .net/ def/ crs/ OGC/ 1 .3/ CRS84 (for coordinates without height);
— http:// www .opengis .net/ def/ crs/ OGC/ 0/ CRS84h (for coordinates with ellipsoidal height).
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6.2.2 Storage CRS
The storage CRS for a spatial feature collection is the CRS identifier that may be used to retrieve
features from that collection without the need to apply a CRS transformation.
Note that coordinates referenced to a dynamic coordinate reference system are ambiguous if the
coordinate epoch is unknown. It is therefore recommended to also provide the coordinate epoch when
the storage CRS is dynamic, such as an ITRF realization or WGS 84. For more information on dynamic
coordinate reference systems and coordinate epoch, please see ISO 19111, Geographic information —
Referencing by coordinates (same as OGC Abstract Specification Topic 2: Referencing by coordinates).
Requirement 3 /req/crs/fc-md-storageCrs
If all features in a spatial feature collection are stored using a particular CRS then the proper-
ty storageCrs shall be specified in the collection object of the spatial feature collection to indicate the identifi-
er for this storage CRS.
Recommendation 2 /rec/crs/fc-md-coordinateEpoch
If the storage CRS of the spatial feature collection is a dynamic coordinate reference system, the proper-
ty storageCrsCoordinateEpoch in the collection object of the spatial feature collection should provide the
coordinate epoch of the coordinates.
This document does not provide a mechanism to associate different coordinate epochs with feature
geometries in a collection. If data with different coordinate epochs is merged in a collection, one option
is to perform point motion operations (PMO) to convert all geometries to the same coordinate epoch.
See ISO 19111, Geographic information — Referencing by coordinates (same as OGC Abstract Specification
Topic 2: Referencing by coordinates), for more information.
Requirement 4 /req/crs/fc-md-storageCrs-valid-value
The value of the storageCrs property shall be one of the CRS identifiers from the list of supported CRS identi-
fiers found in the collection object using the crs property.
The following schema fragment extends the collection object to add the storageCrs and
storageCrsCoordinateEpoch properties.
type: object
required:
- id
- links
properties:
id:
description: identifier of the collection used, for example, in URIs
type: string
example: address
title:
description: human readable title of the collection
type: string
example: address
description:
description: a description of the features in the collection
type: string
example: An address.
links:
type: array
items:
$ref: link.yaml
example:
- href: http://data.example.com/buildings
rel: item
- href: http://example.com/concepts/buildings.html
rel: describedby
type: text/html
extent:
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$ref: extent.yaml
itemType:
description: indicator about the type of the items in the collection (the default
value is 'feature').
type: string
default: feature
crs:
description: the list of CRS identifiers supported by the service
type: array
items:
type: string
default:
- http://www.opengis.net/def/crs/OGC/1.3/CRS84
example:
- http://www.opengis.net/def/crs/OGC/1.3/CRS84
- http://www.opengis.net/def/crs/EPSG/0/4326
storageCrs:
description: the CRS identifier, from the list of supported CRS identifiers, that
may be used to retrieve features from a collection without the need to apply a CRS
transformation
type: string
format: uri
storageCrsCoordinateEpoch:
description: point in time at which coordinates in the spatial feature
collection are referenced to the dynamic coordinate reference system in
`storageCrs`, that may be used to retrieve features from a collection without
the need to apply a change of coordinate epoch. It is expressed as a decimal
year in the Gregorian calendar
type: number
example: '2017-03-25 in the Gregorian calendar is epoch 2017.23'
6.2.3 Global list of CRS identifiers
To prevent unnecessary duplication of lists of supported CRS identifiers in the collection object, a global
list of supported CRS identifiers may be provided as part of the collections object.
This global list of CRS identifiers is not automatically inherited by each collection offered by the service.
Rather the global list of CRS identifiers must be explicitly referenced in the crs property of the collection
object using a JSON Pointer (RFC 6901).
Requirement 5 /req/crs/fc-md-crs-list-global
If the crs property in the collection object of a spatial feature collection includes a JSON Pointer to the global
list of CRS identifiers (#/crs), then all CRS identifiers in the global list shall be valid for the referencing collec-
tion.
Note that only a local JSON Pointer within the same document is supported.
The following schema fragment extends the collections object to add the crs property which contains
the global list of CRS identifiers.
allOf:
- $ref:
'http://schemas.opengis.net/ogcapi/features/part1/1.0/openapi/schemas/collections.yaml'
- type: object
properties:
crs:
description: a global list of CRS identifiers that are supported by spatial feature
collections offered by the service
type: array
items:
type: string
format: uri
The following example illustrates the use of a global list of CRS identifiers.
EXAMPLE Collections object containing a global list of CRS identifiers.
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{
"links": [
{ "href": "http://data.example.org/collections.json",
"rel": "self", "type": "application/json", "title": "this document" },
{ "href": "http://data.example.org/collections.html",
"rel": "alternate", "type": "text/html", "title": "this document as
HTML" },
{ "href": "http://schemas.example.org/1.0/buildings.xsd",
"rel": "describedby", "type": "application/xml", "title": "GML
application schema for Acme Corporation building data" },
{ "href": "http://download.example.org/buildings.gpkg",
"rel": "enclosure", "type": "application/geopackage+sqlite3", "title":
"Bulk download (GeoPackage)", "length": 472546 }
],
"crs": [
"http://www.opengis.net/def/crs/OGC/1.3/CRS84",
"http://www.opengis.net/def/crs/EPSG/0/4326",
"http://www.opengis.net/def/crs/EPSG/0/3857",
"http://www.opengis.net/def/crs/EPSG/0/3395"
],
"collections": [
{
"id": "bonn_buildings",
"title": "Bonn Buildings",
"description": "Buildings in the city of Bonn.",
"extent": {
"spatial": {
"bbox": [ [ 7.01, 50.63, 7.22,
...
SLOVENSKI STANDARD
oSIST prEN ISO 19168-2:2022
01-januar-2022
Geografske informacije - Geoprostorski API za funkcije - 2. del: Koordinatni
referenčni sistemi po referenci (ISO/DIS 19168-2:2021)
Geographic information - Geospatial API for features - Part 2: Coordinate Reference
Systems by Reference (ISO/DIS 19168-2:2021)
Geoinformation - Raumbezogene API für Features - Teil 2: Koordinatenreferenzsystem
durch Referenz (ISO/DIS 19168-2:2021)
Information géographique - API géospatiale pour les entités - Partie 2: Systèmes de
coordonnées de référence par référence (ISO/DIS 19168-2:2021)
Ta slovenski standard je istoveten z: prEN ISO 19168-2
ICS:
07.040 Astronomija. Geodezija. Astronomy. Geodesy.
Geografija Geography
35.240.70 Uporabniške rešitve IT v IT applications in science
znanosti
oSIST prEN ISO 19168-2:2022 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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oSIST prEN ISO 19168-2:2022
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oSIST prEN ISO 19168-2:2022
DRAFT INTERNATIONAL STANDARD
ISO/DIS 19168-2
ISO/TC 211 Secretariat: SIS
Voting begins on: Voting terminates on:
2021-11-03 2022-01-26
Geographic information – Geospatial API for features —
Part 2:
Coordinate Reference Systems by Reference
ICS: 35.240.70
THIS DOCUMENT IS A DRAFT CIRCULATED
This document is circulated as received from the committee secretariat.
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
ISO/CEN PARALLEL PROCESSING
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 19168-2:2021(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
©
PROVIDE SUPPORTING DOCUMENTATION. ISO 2021
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oSIST prEN ISO 19168-2:2022
ISO/DIS 19168-2:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021
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 2021 – All rights reserved
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oSIST prEN ISO 19168-2:2022
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Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Conformance . 2
5 Conventions and Background . 2
6 Requirements Class Coordinate Reference Systems by Reference .2
6.1 Overview . 2
6.2 Discovery . 3
6.2.1 CRS identifier list . 3
6.2.2 Storage CRS . 3
6.2.3 Global list of CRS identifiers . 5
6.3 Query . 7
6.3.1 Parameter bbox-crs . 7
6.3.2 Parameter crs . . 8
6.3.3 Output format considerations . 9
6.3.4 Coordinate reference system information independent of the feature encoding 10
Annex A (normative) Abstract Test Suite .12
Bibliography .16
© ISO 2021 – All rights reserved iii
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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.
A list of all parts in the ISO 19168 series can be found on the ISO website.
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.
iv © ISO 2021 – All rights reserved
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Introduction
OGC API standards define modular API building blocks to spatially enable Web APIs in a consistent way.
The OpenAPI specification is used to define the API building blocks.
The OGC API family of standards is organized by resource type. This document extends the fundamental
API building blocks for interacting with features. The spatial data community uses the term 'feature'
for things in the real world that are of interest.
For those not familiar with the term 'feature,' the explanations on Spatial Things, Features and
Geometry in the W3C/OGC Spatial Data on the Web Best Practice document provide more detail.
OGC API Features provides API building blocks to create, modify and query features on the Web. OGC
API Features is comprised of multiple parts, each of them is a separate standard. This part extends
the core capabilities specified in OGC API - Features - Part 1: Core with the ability to use coordinate
reference system identifiers other than the defaults defined in the core.
By default, every API implementing this document will provide access to a single dataset. Rather than
sharing the data as a complete dataset, the OGC API Features standards offer direct, fine-grained access
to the data at the feature (object) level.
The API building blocks specified in this document are consistent with the architecture of the Web.
In particular, the API design is guided by the IETF HTTP/HTTPS RFCs, the W3C Data on the Web
Best Practices, the W3C/OGC Spatial Data on the Web Best Practices and the emerging OGC Web API
Guidelines. A particular example is the use of the concepts of datasets and dataset distributions as
defined in DCAT and used in schema.org.
A subset of the OGC API family of standards is expected to be published by ISO. For example, this
document is published by ISO as ISO 19168-2. To reflect that only a subset of the OGC API standards
will be published by ISO and to avoid using organization names in the titles of ISO standards, standards
from the "OGC API" series are published by ISO as "Geospatial API," i.e., the title of this document in
OGC is "OGC API - Features - Part 2: Coordinate Reference Systems by Reference" and the title in ISO
is "Geographic Information - Geospatial API for Features - Part 2: Coordinate Reference Systems by
Reference."
For simplicity, this document consistently uses:
— "OGC API" to refer to the family of standards for geospatial Web APIs that in ISO is published as
"Geospatial API;"
— "OGC API - Features" to refer to the multipart standard for features that in ISO is published as
ISO 19168 / "Geographic Information - Geospatial API for Features;"
— "OGC API - Features - Part 1: Core" to refer to the document that in ISO is published as ISO 19168-1
/ "Geographic Information - Geospatial API for Features - Part 1: Core."
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DRAFT INTERNATIONAL STANDARD ISO/DIS 19168-2:2021(E)
Geographic information – Geospatial API for features —
Part 2:
Coordinate Reference Systems by Reference
1 Scope
This document specifies an extension to the Geospatial API for Features — Part 1: Core standard that
defines the behavior of a server that supports the ability to present geometry valued properties in a
response document in one from a list of supported Coordinates Reference Systems (CRS).
Each supported CRS is specified by reference using a uniform resource identifier (URI).
This document specifies:
— How, for each offered feature collection, a server advertises the list of supported CRS identifiers;
— How the coordinates of geometry valued feature properties can be accessed in one of the supported
CRSs;
— How features can be accessed from the server using a bounding box specified in one of the supported
CRSs; and
— How a server can declare the coordinate reference system used to present feature resources.
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 19168-1:2020, Geographic information — Geospatial API for features — Part 1: Core
3 Terms and definitions
For the purposes of this document, the following additional terms and definitions apply in addition to
the terms defined in ISO 19168-1:2020, Geographic information — Geospatial API for features — Part 1:
Core.
ISO and IEC maintain terminology 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
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, definition 3.1.5]
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3.2
coordinate reference system (CRS)
coordinate system that is related to an object by a datum
[SOURCE: ISO 19111:2019, definition 3.1.9]
3.3
coordinate system
set of mathematical rules for specifying how coordinates are to be assigned to points
[SOURCE: ISO 19111:2019, definition 3.1.11]
3.4
feature
abstraction of real world phenomena
Note 1 to entry: More details about the term 'feature' may be found in the W3C/OGC Spatial Data on the Web Best
Practice in the section 'Spatial Things, Features and Geometry'.
[SOURCE: ISO 19101-1:2014]
3.5
feature collection
collection
set of features from a dataset
3.6
spatial feature collection
spatial collection
feature collection that includes one or more geometry-valued properties
4 Conformance
This standard defines one requirements class Coordinate Reference Systems by Reference. The
standardization target is "Web APIs".
The URI of the associated conformance class is http:// www .opengis .net/ spec/ ogcapi -features -2/ 1 .0/
conf/ crs.
Conformance with this standard shall be checked using all the relevant tests specified in Annex A of
this document. The framework, concepts, and methodology for testing, and the criteria to be achieved
to claim conformance are specified in the OGC Compliance Testing Policies and Procedures and the OGC
Compliance Testing web site.
5 Conventions and Background
See ISO 19168-1:2020, Clauses 5 and 6.
6 Requirements Class Coordinate Reference Systems by Reference
6.1 Overview
Requirements Class
http:// www .opengis .net/ spec/ ogcapi -features -2/ 1 .0/ req/ crs
Target type Web API
Dependency OGC API - Features - Part 1: Core, Requirements Class 'core'
2 © ISO 2021 – All rights reserved
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ISO/DIS 19168-2:2021(E)
The OGC API - Features - Part 1: Core standard defines support for only two coordinate reference
systems:
— WGS 84 longitude, latitude;
— WGS 84 longitude, latitude, ellipsoidal height.
This extension defines the behavior of a server that supports additional coordinate reference systems.
Requirement 1 /req/crs/crs-uri
Each CRS supported by a server SHALL be referenceable by a uniform resource identifier (i.e., a URI).
Recommendation 1 /rec/crs/crs-format-model
Servers that implement this extension SHOULD be able to recognize and generate CRS identifiers with the
following format model:
http://www.opengis.net/def/crs/authority/version/code
In this format model, the token {authority} is a placeholder for a value that designates to authority responsi-
ble for the definition of this CRS. Typical values include "EPSG" and "OGC".
The token {version} is a placeholder for the specific version of the CRS definition or 0 for un-versioned CRS
definitions.
The token {code} is a placeholder for the authority’s code for the CRS.
For more information, see section 6.2 in OGC Name Type Specification, Part 1.
Note that while the EPSG register itself is versioned, the registered items are not versioned and the
"version" is always "0" in URIs of the authority "EPSG".
6.2 Discovery
6.2.1 CRS identifier list
Requirement 2 /req/crs/fc-md-crs-list
A The crs property in the collection object of a spatial feature collection SHALL contain the
identifiers for the list of CRSs supported by the server for that collection.
B This list SHALL include the default(s) defined in OGC API - Features - Part 1: Core.
The list has to include the default CRS — that is the CRS used unless something else is explicitly
requested — is defined in ISO 19168-1:2020, Geographic information — Geospatial API for features —
Part 1: Core as:
— http:// www .opengis .net/ def/ crs/ OGC/ 1 .3/ CRS84 (for coordinates without height);
— http:// www .opengis .net/ def/ crs/ OGC/ 0/ CRS84h (for coordinates with ellipsoidal height).
6.2.2 Storage CRS
The storage CRS for a spatial feature collection is the CRS identifier that may be used to retrieve
features from that collection without the need to apply a CRS transformation.
Note that coordinates referenced to a dynamic coordinate reference system are ambiguous if the
coordinate epoch is unknown. It is therefore recommended to also provide the coordinate epoch when
the storage CRS is dynamic, such as an ITRF realization or WGS 84. For more information on dynamic
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coordinate reference systems and coordinate epoch, please see ISO 19111:2019 Geographic information
- Referencing by coordinates (same as OGC Abstract Specification Topic 2: Referencing by coordinates).
Requirement 3 /req/crs/fc-md-storageCrs
If all features in a spatial feature collection are stored using a particular CRS then the proper-
ty storageCrs SHALL be specified in the collection object of the spatial feature collection to indicate the
identifier for this storage CRS.
Recommendation 2 /rec/crs/fc-md-coordinateEpoch
If the storage CRS of the spatial feature collection is a dynamic coordinate reference system, the proper-
ty storageCrsCoordinateEpoch in the collection object of the spatial feature collection SHOULD provide the
coordinate epoch of the coordinates.
This document does not provide a mechanism to associate different coordinate epochs with feature
geometries in a collection. If data with different coordinate epochs is merged in a collection, one option
is to perform point motion operations (PMO) to convert all geometries to the same coordinate epoch.
See ISO 19111:2019 Geographic information - Referencing by coordinates (same as OGC Abstract
Specification Topic 2: Referencing by coordinates) for more information.
Requirement 4 /req/crs/fc-md-storageCrs-valid-value
The value of the storageCrs property SHALL be one of the CRS identifiers from the list of supported CRS iden-
tifiers found in the collection object using the crs property.
The following schema fragment extends the collection object to add the storageCrs and
storageCrsCoordinateEpoch properties.
type: object
required:
- id
- links
properties:
id:
description: identifier of the collection used, for example, in URIs
type: string
example: address
title:
description: human readable title of the collection
type: string
example: address
description:
description: a description of the features in the collection
type: string
example: An address.
links:
type: array
items:
$ref: link.yaml
example:
- href: http://data.example.com/buildings
rel: item
- href: http://example.com/concepts/buildings.html
rel: describedby
type: text/html
extent:
$ref: extent.yaml
itemType:
description: indicator about the type of the items in the collection (the default
value is 'feature').
type: string
default: feature
crs:
description: the list of CRS identifiers supported by the service
type: array
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items:
type: string
default:
- http://www.opengis.net/def/crs/OGC/1.3/CRS84
example:
- http://www.opengis.net/def/crs/OGC/1.3/CRS84
- http://www.opengis.net/def/crs/EPSG/0/4326
storageCrs:
description: the CRS identifier, from the list of supported CRS identifiers, that
may be used to retrieve features from a collection without the need to apply a CRS
transformation
type: string
format: uri
storageCrsCoordinateEpoch:
description: point in time at which coordinates in the spatial feature collection are
referenced to the dynamic coordinate reference system in `storageCrs`, that may be used
to retrieve features from a collection without the need to apply a change of coordinate
epoch. It is expressed as a decimal year in the Gregorian calendar
type: number
example: '2017-03-25 in the Gregorian calendar is epoch 2017.23'
6.2.3 Global list of CRS identifiers
To prevent unnecessary duplication of lists of supported CRS identifiers in the collection object, a global
list of supported CRS identifiers may be provided as part of the collections object.
This global list of CRS identifiers is not automatically inherited by each collection offered by the service.
Rather the global list of CRS identifiers must be explicitly referenced in the crs property of the collection
object using a JSON Pointer (RFC 6901).
Requirement 5 /req/crs/fc-md-crs-list-global
If the crs property in the collection object of a spatial feature collection includes a JSON Pointer to the global
list of CRS identifiers (#/crs), then all CRS identifiers in the global list SHALL be valid for the referencing
collection.
Note that only a local JSON Pointer within the same document is supported.
The following schema fragment extends the collections object to add the crs property which contains
the global list of CRS identifiers.
allOf:
- $ref:
'http://schemas.opengis.net/ogcapi/features/part1/1.0/openapi/schemas/collections.yaml'
- type: object
properties:
crs:
description: a global list of CRS identifiers that are supported by spatial feature
collections offered by the service
type: array
items:
type: string
format: uri
The following example illustrates the use of a global list of CRS identifiers.
EXAMPLE Collections object containing a global list of CRS identifiers.
{
"links": [
{ "href": "http://data.example.org/collections.json",
"rel": "self", "type": "application/json", "title": "this document" },
{ "href": "http://data.example.org/collections.html",
"rel": "alternate", "type": "text/html", "title": "this document as HTML" },
{ "href": "http://schemas.example.org/1.0/buildings.xsd",
"rel": "describedby", "type": "application/xml", "title": "GML application schema
for Acme Corporation building data" },
{ "href": "http://download.example.org/buildings.gpkg",
"rel": "enclosure", "type": "application/geopackage+sqlite3", "title": "Bulk
download (GeoPackage)", "length": 472546 }
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],
"crs": [
"http://www.opengis.net/def/crs/OGC/1.3/CRS84",
"http://www.opengis.net/def/crs/EPSG/0/4326",
"http://www.opengis.net/def/crs/EPSG/0/3857",
"http://www.opengis.net/def/crs/EPSG/0/3395"
],
"collections": [
{
"id": "bonn_buildings",
"title": "Bonn Buildings",
"description": "Buildings in the city of Bonn.",
"extent": {
"spatial": {
"bbox": [ [ 7.01, 50.63, 7.22, 50.78 ] ]
},
"temporal": {
"interval": [ [ "2010-02-15T12:34:56Z", null ] ]
}
},
"links": [
{ "href":
"http://data.example.org/collections/bonn_buildings/items",
"rel": "items", "type": "application/geo+json",
"title": "Bonn Buildings" },
{ "href": "https://creativecommons.org/publicdomain/zero/1.0/",
"rel": "license", "type": "text/html",
"title": "CC0-1.0" },
{ "href":
"https://creativecommons.org/publicdomain/zero/1.0/rdf",
"rel": "license", "type": "application/rdf+xml",
"title": "CC0-1.0" }
],
"crs": [
"#/crs",
"http://www.opengis.net/def/crs/EPSG/0/4258",
"http://www.opengis.net/def/crs/EPSG/0/25831",
"http://www.opengis.net/def/crs/EPSG/0/25832"
]
},
{
"id": "tor_buildings",
"title": "Toronto Buildings",
"description": "Buildings in the city of Toronto.",
"extent": {
"spatial": {
"bbox": [ [ -79.62, 43.58, -79.12, 43.87 ] ]
},
"temporal": {
"interval": [ [ "2010-02-15T12:34:56Z", null ] ]
}
},
"links": [
{ "href":
"http://data.example.org/collections/tor_buildings/items",
"rel": "items", "type": "application/geo+json",
"title": "Toronto Buildings" },
{ "href": "https://creativecommons.org/publicdomain/zero/1.0/",
"rel": "license", "type": "text/html",
"title": "CC0-1.0" },
{ "href":
"https://creativecommons.org/publicdomain/zero/1.0/rdf",
"rel": "license", "type": "application/rdf+xml",
"title": "CC0-1.0" }
],
"crs": [
"#/crs"
]
},
{
"id": "dc_buildings",
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"title": "Washington DC Buildings",
"description": "Buildings in the city of Washington DC.",
"extent": {
"spatial": {
"bbox": [ [ -77.12, 38.80, -76.89, 39.01 ] ]
},
"temporal": {
"interval": [ [ "2010-02-15T12:34:56Z", null ] ]
}
},
"links": [
{ "href":
"http://data.example.org/collections/dc_buildings/items",
"rel": "items", "type": "application/geo+json",
"title": "DC Buildings" },
{ "href": "https://creativecommons.org/publicdomain/zero/1.0/",
"rel": "license", "type": "text/html",
"title": "CC0-1.0" },
{ "href":
"https://creativecommons.org/publicdomain/zero/1.0/rdf",
"rel": "license", "type": "application/rdf+xml",
"title": "CC0-1.0" }
],
"crs": [
"http://www.opengis.net/def/crs/OGC/1.3/CRS84"
]
}
]
}
In the above example, the bonn_buildings collection is offered in all the CRSs specified in the global list
plus three other CRSs.
The tor_buildings collection is offered in the CRSs specified in the global list.
The dc_buildings collection is only offered in the default CRS (i.e., WGS 84 longitude, latitude).
6.3 Query
6.3.1 Parameter bbox-crs
The bbox-crs parameter may be used to assert the CRS used for the coordinate values of
the bbox parameter.
Requirement 6 /req/crs/fc-bbox-crs-definition
Each GET request on a 'features' resource SHALL support a query parameter bbox-crs with the following
characteristics:
name: bbox-crs
in: query
required: false
schema:
type: string
format: uri
style: form
explode: false
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Requirement 7 /req/crs/fc-bbox-crs-valid-value
A If the value of the bbox-crs parameter is not one of the CRS identifiers from the list of
supported CRS identifiers, then the server SHALL respond with the HTTP status code
400.
B The list of supported CRS identifiers is found in the collection object using the crs prop-
ert
...
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