Geographic information -- Place Identifier (PI) architecture -- Part 2: Place Identifier (PI) linking

This document defines the following three mechanisms for linking Place Identifiers (PIs) (see ISO 19155) to features or objects existing in other encodings:
-Id attribute of a GML object (gml:id) as defined in ISO 19136;
- Universally Unique Identifier (UUID) as defined in IETF RFC 4122;
- Uniform Resource Locator (URL) as defined in IETF RFC 1738.
These PI linking mechanisms are enabled using xlink: href as defined in W3C XML Linking Language (XLink). While the identifiers of these features or objects can sometimes identify a place, within the scope of this document, the identifiers of features or objects existing in other encoding domains are referred to conceptually as other identifiers. This document further defines that when PIs are encoded, as specified in ISO 19155, using the Geography Markup Language (GML) (ISO 19136), they are linked using gml:id to other GML encoded features. The details of encoding GML instances using gml:id are specified in a normative annex. Additional normative annexes define encodings for linking Place Identifiers to other identifiers using UUID and URL and present examples for their use. This document is applicable to location-based services, linked open data, robotic assisted services and other application domains that require a relationship between PIs and objects in either the real or virtual world. This document is not about creating a registry of Place Identifiers linked to specific features or objects, and support of linking mechanisms other than gml:id, UUID, and URL is out of the scope of this document.

Information géographique -- Architecture d'identifiants de lieu (IL) -- Partie 2: Liaison didentifiants de lieu (IL)

Geografske informacije - Arhitektura lokacijskih identifikatorjev - 2. del: Povezovalni lokacijski identifikator

Ta dokument določa naslednje tri mehanizme za povezovanje lokacijskih identifikatorjev (PI) (glej ISO 19155) za funkcije ali objekte, ki obstajajo v drugih šifriranjih:
– atribut ID za objekt GML (gml:id), kot je opredeljen v standardu ISO 19136;
– globalni enolični identifikator (UUID), kot je opredeljen v standardu IETF RFC 4122;
– spletni naslov (URL), kot je opredeljen v standardu IETF RFC 1738.
Ti mehanizmi povezovanja lokacijskih identifikatorjev so omogočeni z uporabo povezave xlink: href, kot je opredeljena v povezovalnem jeziku W3C XML (XLink). Medtem ko lahko identifikatorji teh funkcij ali objektov včasih identificirajo lokacijo, se na področju uporabe tega dokumenta identifikatorji funkcij ali objektov, ki obstajajo v drugih domenah šifriranja, konceptualno obravnavajo kot drugi identifikatorji. Ta dokument nadalje določa naslednje: ko so lokacijski identifikatorji šifrirani, kot je določeno v standardu ISO 19155, z uporabo zemljepisnega označevalnega jezika (GML) (ISO 19136), se z drugimi šifriranimi funkcijami GML povezujejo na podlagi identifikatorja gml:id. Podrobnosti primerkov šifriranja GML z uporabo identifikatorja gml:id so opredeljene v normativnem dodatku. Dodatne normativni dodatki opredeljujejo šifriranja za povezovanje lokacijskih identifikatorjev z drugimi identifikatorji z uporabo identifikatorjev UUID in URL ter navajajo primere za njihovo uporabo. Ta dokument se uporablja za lokacijske storitve, povezane z odprtimi podatki, robotskimi pomožnimi storitvami in drugimi domenami uporabe, ki zahtevajo razmerje med lokacijskimi identifikatorji in objekti v resničnem ali virtualnem svetu. Ta dokument ne obravnava ustvarjanja registra lokacijskih identifikatorjev, povezanih z določilnimi funkcijami ali objekti, podpora za povezovalne mehanizme, ki niso gml:id, UUID in URL, pa je zunaj področja uporabe tega dokumenta.

General Information

Status
Published
Public Enquiry End Date
30-Dec-2016
Publication Date
08-Dec-2019
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
26-Nov-2019
Due Date
31-Jan-2020
Completion Date
09-Dec-2019

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INTERNATIONAL ISO
STANDARD 19155-2
First edition
2017-08
Geographic information — Place
Identifier (PI) architecture —
Part 2:
Place Identifier (PI) linking
Information géographique — Architecture d’identifiants de lieu (IL) —
Partie 2: Liaison d’identifiants de lieu (IL)
Reference number
ISO 19155-2:2017(E)
ISO 2017
---------------------- Page: 1 ----------------------
ISO 19155-2:2017(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2017, Published in Switzerland

All rights reserved. Unless otherwise specified, 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
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2017 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 19155-2:2017(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 2

4 Abbreviated terms .............................................................................................................................................................................................. 2

4.1 Abbreviated terms ............................................................................................................................................................................... 2

4.2 UML Notation ........................................................................................................................................................................................... 3

4.3 Backward compatibility .................................................................................................................................................................. 3

5 Conformance ............................................................................................................................................................................................................. 3

5.1 General ........................................................................................................................................................................................................... 3

5.2 Linking mechanism: gml:id .......................................................................................................................................................... 3

5.3 Linking mechanism: UUID ............................................................................................................................................................ 3

5.4 Linking mechanism: URL ............................................................................................................................................................... 3

6 Place Identifier (PI) concept .................................................................................................................................................................... 4

6.1 General ........................................................................................................................................................................................................... 4

6.2 PI structure................................................................................................................................................................................................. 4

7 PI linking ....................................................................................................................................................................................................................... 4

7.1 Overview ...................................................................................................................................................................................................... 4

7.2 PI linking directionality ................................................................................................................................................................... 5

7.3 PI linking model ..................................................................................................................................................................................... 7

8 PI linking mechanisms ................................................................................................................................................................................... 7

8.1 Overview ...................................................................................................................................................................................................... 7

8.2 Linking mechanism: gml:id .......................................................................................................................................................... 8

8.2.1 Overview ................................................................................................................................................................................. 8

8.2.2 Linking from a PI ............................................................................................................................................................. 8

8.2.3 Linking to a PI ..................................................................................................................................................................... 8

8.2.4 Instance examples using gml:id .......................................................................................................................... 8

8.3 Linking mechanism: UUID ............................................................................................................................................................ 9

8.4 Linking mechanism: URL ............................................................................................................................................................... 9

Annex A (normative) Abstract test suite .......................................................................................................................................................10

Annex B (normative) Encoding using gml:id to link with GML ..............................................................................................11

Annex C (normative) Encoding using gml:id to link with GML application schemas ......................................16

Annex D (normative) Encoding using UUID for linking .................................................................................................................19

Annex E (normative) Encoding using URL for linking .....................................................................................................................21

Annex F (informative) Use case examples ....................................................................................................................................................22

Annex G (informative) RDF examples of linking PIs ..........................................................................................................................27

Bibliography .............................................................................................................................................................................................................................34

© ISO 2017 – All rights reserved iii
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ISO 19155-2:2017(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 on 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 the following

URL: w w w . i s o .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 19155 series can be found on the ISO website.
iv © ISO 2017 – All rights reserved
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ISO 19155-2:2017(E)
Introduction

The Place Identifier (PI) architecture (ISO 19155) defined the conceptual model of a place and

specified normative encodings, for Place Identifiers, not specific to any type of geographic feature. In

this document, three mechanisms are presented that define how Place Identifiers can be linked with

features or objects in other encodings. Even though the identifiers of those features or objects may not

specifically be a place, they may be referred to conceptually as “other identifiers.”

Figure 1 depicts the abstractions of linking mechanisms among feature/object encoding rules.

a) Without the use of a Place Identifier b) With the use of a Place Identifier
Key
encoding rules
linkages
Figure 1 — Linkages with other encoding rules

The linking mechanisms presented in this document are based on accepted information technology

for object identification and reference using gml:id, UUID, or URL. By using these linking mechanisms

with the rules defined here, and according to the type of encoding rule being linked to, Place Identifiers

can more uniformly be related to features and objects — other identifiers — in other encodings.

This extends the functionality of those other identifiers, in different encodings, by linking with Place

Identifiers encoded in GML.

Existing PI data can complement a range of other encodings through the use of the linking mechanisms

defined in this document.

For example, a group of Place Identifiers representing stores in a shopping mall can be associated with

the specific locations inside the shopping mall represented by a GML data set.
© ISO 2017 – All rights reserved v
---------------------- Page: 5 ----------------------
INTERNATIONAL STANDARD ISO 19155-2:2017(E)
Geographic information — Place Identifier (PI)
architecture —
Part 2:
Place Identifier (PI) linking
1 Scope

This document defines the following three mechanisms for linking Place Identifiers (PIs) (see ISO 19155)

to features or objects existing in other encodings:
— Id attribute of a GML object (gml:id) as defined in ISO 19136;
— Universally Unique Identifier (UUID) as defined in IETF RFC 4122;
— Uniform Resource Locator (URL) as defined in IETF RFC 1738.

These PI linking mechanisms are enabled using xlink: href as defined in W3C XML Linking Language

(XLink).

While the identifiers of these features or objects can sometimes identify a place, within the scope of

this document, the identifiers of features or objects existing in other encoding domains are referred to

conceptually as other identifiers.

This document further defines that when PIs are encoded, as specified in ISO 19155, using the

Geography Markup Language (GML) (ISO 19136), they are linked using gml:id to other GML encoded

features. The details of encoding GML instances using gml:id are specified in a normative annex.

Additional normative annexes define encodings for linking Place Identifiers to other identifiers using

UUID and URL and present examples for their use.

This document is applicable to location-based services, linked open data, robotic assisted services

and other application domains that require a relationship between PIs and objects in either the real or

virtual world.

This document is not about creating a registry of Place Identifiers linked to specific features or

objects, and support of linking mechanisms other than gml:id, UUID, and URL is out of the scope of this

document.
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 19103, Geographic information — Conceptual schema language
ISO 19136:2007, Geographic information — Geography Markup Language
ISO 19155:2012, Geographic information — Place Identifier (PI) architecture
IETF, Universally Unique IDentifier (UUID) URN Namespace, RFC 4122, July 2005
IETF, Uniform Resource Locators (URL), RFC 1738, December 1994
© ISO 2017 – All rights reserved 1
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ISO 19155-2:2017(E)
W3C XML Linking Language (XLink) Version 1.1 — Recommendation, 06 May 2010
3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 19155 and the following apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— IEC Electropedia: available at http:// www .electropedia .org/
— ISO Online browsing platform: available at http:// www .iso .org/ obp
3.1
Place Identifier (PI) link

relationship established between PIs and other identifiers in different encoding domains

Note 1 to entry: While the identifiers of these features or objects can sometimes identify a place, within the

scope of this document, the identifiers of features or objects existing in other encoding domains are referred to

conceptually as “other identifiers”.

Note 2 to entry: These “other identifiers” can exist outside of the PI architecture.

3.2
Place Identifier (PI) linking mechanism
means used to define a place identifier (PI) link (3.1)
4 Abbreviated terms
4.1 Abbreviated terms
BIM Building Information Model
CSV comma-separated values
IFC Industry Foundation Class
GUID Globally Unique IDentifier
OGC Open Geospatial Consortium
PI Place Identifier
RDF Resource Description Framework
SVG Scalable Vector Graphics
UML Unified Modeling Language
URI Uniform Resource Identifier
URL Uniform Resource Locator
URN Uniform Resource Name
UUID Universally Unique IDentifier
XML eXtensible Markup Language
2 © ISO 2017 – All rights reserved
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ISO 19155-2:2017(E)
4.2 UML Notation

In this document, conceptual schemas are presented in the Unified Modeling Language (UML). The user

shall refer to ISO 19103 for the specific profile of UML used in this document.
4.3 Backward compatibility

This document uses the concepts defined in the Place Identifier (PI) Architecture (ISO 19155) without

modification. Therefore, no backward compatibility issues exist in this document.

5 Conformance
5.1 General

This document defines three conformance classes, specified in 5.2 to 5.4, matching the requirements

classes of the three linking mechanisms defined in Clause 8. Any PI linking mechanism for which

conformance with this document is claimed shall pass all of the requirements of the abstract test suite

specified in Annex A.
5.2 Linking mechanism: gml:id

PI linking for which gml:id conformance is claimed shall pass all of the requirements specified in the

abstract test suite in A.2.
Table 1 — Conformance class: Linking mechanism: gml:id
Conformance class /conf/19155-2/5/5.2
Dependency A.1
Requirements /req/linking_mechanism/GML_ID
Tests A.2
5.3 Linking mechanism: UUID

PI linking for which UUID conformance is claimed shall pass all of the requirements specified in the

abstract test suite in A.3.
Table 2 — Conformance class: Linking mechanism: UUID
Conformance class /conf/19155-2/5/5.3
Dependency A.1
Requirements /req/linking_mechanism/UUID
Tests A.3
5.4 Linking mechanism: URL

PI linking for which URL conformance is claimed shall pass all of the requirements specified in the

abstract test suite in A.4.
Table 3 — Conformance class: Linking mechanism: URL
Conformance class /conf/19155-2/5/5.4
Dependency A.1
Requirements /req/linking_mechanism/URL
Tests A.4
© ISO 2017 – All rights reserved 3
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ISO 19155-2:2017(E)
6 Place Identifier (PI) concept
6.1 General

A “place” is defined as an identifiable part of any space (ISO 19155), either in the real world or

virtual world.

ISO 19155:2012, 6.1 states that the same place can be identified with multiple Place Identifiers (PIs).

If the place is identified with coordinates, it is called “position” and if the place is identified with

geographic identifiers, it is called “location.” Additionally, the place may be identified with online

resource identifiers such as URI.

In ISO 19109:2015, 7.4, “position” is a spatial attribute of a feature, “location” is a location attribute of a

feature, and a virtual identifier, such as a URI, is a thematic attribute of a feature. Therefore, a PI can be

considered as an attribute of a feature.
6.2 PI structure

Figure 2 shows the structure of the PI, as defined in ISO 19155:2012, 7.2.2. The PI_PlaceIdentifier type

is the basic data type for the PI.
Figure 2 — PI_PlaceIdentifier
The PI_PlaceIdentifier class defines the following attributes.
a) The attribute rs specifies the reference system of the PI.

b) The attribute value is the identifier for a place and is unique within the context of the defined

reference system.

c) The optional attribute validPeriod specifies the period in which the identifier is valid for the place.

The validPeriod can be used to set the expiration of the identifier which can be validated through

implementation. The property of uniqueness of the identifier is determined by the reference system (rs).

7 PI linking
7.1 Overview
There are two main concepts that are standardized in this document.

The first concept is a mechanism for connecting PIs which identify the same place, where the connection

is directly embedded into the PI.

PI matching (ISO 19155:2012, 4.11) is the matching of multiple PIs that represent the same place. This

matching is accomplished through the use of the PI matching service (ISO 19155:2012, 7.3.2) and when

implemented, is performed within the PI architecture. The logical structure of “PI matching” is shown

in ISO 19155:2012, Figure 8, where a “PI_MatchedPISet” connects more than two “PI_PlaceIdentifier”s

which identify the same place. The one way association from “PI_MatchedPISet” to “PI_PlaceIdentifier”

enables users to make links independently with the instances of PI_PlaceIdentifier, and the data

4 © ISO 2017 – All rights reserved
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ISO 19155-2:2017(E)

independence of the connection ensures the use of existing place identifiers because existing data need

not change their schemas.

However, in many situations, relationships exist between PIs encoded using ISO 19155 and other

identifiers in different encodings, existing independently or outside of the PI architecture. As these

other identifiers are usually features or objects in different encodings, it is not possible for them to be

included in or managed by the PI architecture. In these situations, users may want to simply embed the

connection into their PI. Depending on the encodings of these other identifiers, a set of clearly defined

mechanisms is required to expose and use those other identifiers for PI linking.

This is referred to as a Place Identifier (PI) link (3.1), similarly, a Place Identifier (PI) linking mechanism

(3.2) is a means of defining a Place Identifier (PI) link.

While one specific linking mechanism is not suitable for all other identifiers in other encodings,

similarities in linking mechanisms exist, such as the use of XLink for XML-based encodings.

The second concept standardized by this document is the structure of data instances for PI Linking.

This document defines how to use existing constructs to enable linking to PIs without modification to

those encoding rules for object identification and reference.
7.2 PI linking directionality

In this document, all links are directional. In cases where a bi-directional link is required, two distinct

directional links shall be made, one in each direction.

/req/linking_directionality/direction- where a bi-directional link is required, two distinct

al_links directional links shall be made, one in each direction

A combination of directionality and encoding format limits the applicability of this document, as shown

in the following cases:

a) if both identifiers are encoded in GML (ISO 19136:2007), the linking is normative;

b) if one identifier is in another encoding, the linking from a PI to that identifier is normative;

c) if one identifier is in another encoding, the linking from that identifier to a PI is informative.

In Figure 3, the direction of the link between a PI encoded using ISO 19155 and an identifier in another

encoding is shown using an arrow representing the directionality of the link. In addition, normative

linking is shown using a solid line and informative linking is shown using a dashed line.

The normative linking mechanisms are:

a) gml:id: for linking between a PI and another identifier encoded in GML, see 8.2.2 and 8.2.3;

b) UUID or URL: for linking from a PI to an identifier in another encoding, see 8.3 and 8.4, respectively.

Figure 3 depicts linking to PIs from IFC(BIM) and SVG using IfcDocumentReference and rdf: resource

as linking mechanisms. These mechanisms are shown as informative because those encodings are not

being modified by this document.
© ISO 2017 – All rights reserved 5
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ISO 19155-2:2017(E)
Key
encoding rules (examples in this document)
other encoding rules
linking methods (normative)
linking methods (informative)
ISO 19155-2 scope (normative content)
ISO 19155 (normative PI encoding)
Figure 3 — Overview of content in ISO 19155-2
6 © ISO 2017 – All rights reserved
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ISO 19155-2:2017(E)
7.3 PI linking model
The conceptual model in Figure 4 defines the structure of PI linking.

The PI_PlaceIdentifier class defined in this document is an extended data type for the Place Identifier

which enables users to connect a PI directly to other PIs.

The PI_PlaceIdentifier class also has a mandatory association “Linking” in addition to the derived three

attributes. The association “Linking” is a mechanism for connecting PIs which identify the same place,

where the connection is directly embedded into the PI.

NOTE While “PI_MatchedPISet” defined in ISO 19155 has an association to connect more than two “PI_

PlaceIdentifier”s which identify the same place, “PI_PlaceIdentifier” defined in ISO 19155 itself does not have a

property to connect other “PI_PlaceIdentifier”s.
Figure 4 — PI linking model
8 PI linking mechanisms
8.1 Overview

This document defines three mechanisms for linking Place Identifiers to features or objects existing in

other encodings. These PI linking mechanisms are enabled using the following information technologies

for object identification and reference:
— using a gml:id linking both from and to a PI, see 8.2;
— using a Universally Unique Identifier (UUID) linking from a PI, see 8.3;
— using a Uniform Resource Locator (URL) linking from a PI, see 8.4.

When using the linking mechanisms defined in this document, the PIs shall be encoded using ISO 19136,

which is the recommended normative encoding option, as specified in ISO 19155:2012, Annex B.

/req/linking_mechanisms/encoding existing Place Identifiers shall be encoded using ISO 19136

as specified in ISO 19155:2012, Annex B
© ISO 2017 – All rights reserved 7
---------------------- Page: 12 ----------------------
ISO 19155-2:2017(E)
Implementation requirements are specified in 8.2, 8.3, and 8.4.

The encodings presented in this document are suitable for linking with a PI but do not represent a

conclusive list and other encodings may also be suitable for linking with a PI using one of the defined

mechanisms. Linkages may also exist directly between multiple encodings and can make use of a PI.

For the purpose of this document, linkages not using a PI are out of scope.
Use case examples of PI linking are presented in Annex F.

The PI architecture and PI linking concepts have implications for use in the semantic web and linked

data. To provide additional descriptions, Annex G includes RDF examples for PIs and PI linking.

8.2 Linking mechanism: gml:id
8.2.1 Overview

If gml:id is used, linking is defined as bi-directional, both from and to a PI, and linking Place Identifiers

with other features encoded in GML and related application schema is specified based on the following

content from ISO 19136:2007, 8.1:

Xlink components are used in GML to implement associations between objects by reference. GML

property elements (ISO 19136:2007, 7.2.3) may carry XLink attributes, which support the encoding of

an association relationship by reference, the name of the property element denoting the target role in

the association.

/req/linking_mechanisms/GML_ID gml:id shall be used when linking to Place Identifiers

encoded in GML
8.2.2 Linking from a PI

An xlink: href property in a PI instance defines a link that shall be used to point to a discrete GML

instance and the value in that discrete GML instance is referenced by traversing the link.

/req/linking_mechanisms/GML_ID/from- the xlink: href property in a PI instance shall use a

a-PI gml:id to define a link that points to a discrete GML
instance
8.2.3 Linking to a PI

The converse is also defined by this document, where an xlink: href property in a GML instance defines

a link that shall be used to point to a discrete PI instance and the value in that discrete PI instance is

referenced by traversing the link.

/req/linking_mechanisms/ GML_ID/to-a-PI the xlink: href property in a GML instance shall use

a gml:id to define a link that points to a discrete PI
instance
8.2.4 Instance examples using gml:id

Examples showing the use of gml:id for linking between PIs and other GML encoded instances are

presented in Annex B.

GML feature instances conforming to application schemas, such as OGC CityGML (OGC 12-019) and OGC

IndoorGML 1.0 (OGC 14-005r3), may also be linked with a PI, as shown in Annex C.
8 © ISO 2017 – All rights reserved
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ISO 19155-2:2017(E)
8.3 Linking mechanism: UUID

If UUID is used, linking is defined in a single direction, from a PI, where a Namespace URN shall conform

to IETF RFC 4122, and a Universally Unique Identifier (UUID) is stored in the attribute of the linkedPI,

as shown in the following example fragment.

TokyoInternationalAirport_POI_list.net
Terminal1_Gate15


/req/linking_mechanisms/UUID when a UUID is used, the xlink: href property in a PI

instance shall use a UUID to define a link from a PI
that points to a discrete instance of another identifier
Examples showing the use of UUID for linking PIs are presented in Annex D.
8.4 Linking mechanism: URL

If a URL is used, linking is defined in a single direction, from a PI, where a URL conforming to IETF

RFC 1738, is stored in the attribute of the linkedPI, as shown in the following example fragment.


gazett
...

SLOVENSKI STANDARD
SIST ISO 19155-2:2020
01-januar-2020
Geografske informacije - Arhitektura lokacijskih identifikatorjev - 2. del:
Povezovalni lokacijski identifikator

Geographic information -- Place Identifier (PI) architecture -- Part 2: Place Identifier (PI)

linking

Information géographique -- Architecture d'identifiants de lieu (IL) -- Partie 2: Liaison

didentifiants de lieu (IL)
Ta slovenski standard je istoveten z: ISO 19155-2:2017
ICS:
07.040 Astronomija. Geodezija. Astronomy. Geodesy.
Geografija Geography
35.240.70 Uporabniške rešitve IT v IT applications in science
znanosti
SIST ISO 19155-2:2020 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
SIST ISO 19155-2:2020
---------------------- Page: 2 ----------------------
SIST ISO 19155-2:2020
INTERNATIONAL ISO
STANDARD 19155-2
First edition
2017-08
Geographic information — Place
Identifier (PI) architecture —
Part 2:
Place Identifier (PI) linking
Information géographique — Architecture d’identifiants de lieu (IL) —
Partie 2: Liaison d’identifiants de lieu (IL)
Reference number
ISO 19155-2:2017(E)
ISO 2017
---------------------- Page: 3 ----------------------
SIST ISO 19155-2:2020
ISO 19155-2:2017(E)
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© ISO 2017, Published in Switzerland

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Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 2

4 Abbreviated terms .............................................................................................................................................................................................. 2

4.1 Abbreviated terms ............................................................................................................................................................................... 2

4.2 UML Notation ........................................................................................................................................................................................... 3

4.3 Backward compatibility .................................................................................................................................................................. 3

5 Conformance ............................................................................................................................................................................................................. 3

5.1 General ........................................................................................................................................................................................................... 3

5.2 Linking mechanism: gml:id .......................................................................................................................................................... 3

5.3 Linking mechanism: UUID ............................................................................................................................................................ 3

5.4 Linking mechanism: URL ............................................................................................................................................................... 3

6 Place Identifier (PI) concept .................................................................................................................................................................... 4

6.1 General ........................................................................................................................................................................................................... 4

6.2 PI structure................................................................................................................................................................................................. 4

7 PI linking ....................................................................................................................................................................................................................... 4

7.1 Overview ...................................................................................................................................................................................................... 4

7.2 PI linking directionality ................................................................................................................................................................... 5

7.3 PI linking model ..................................................................................................................................................................................... 7

8 PI linking mechanisms ................................................................................................................................................................................... 7

8.1 Overview ...................................................................................................................................................................................................... 7

8.2 Linking mechanism: gml:id .......................................................................................................................................................... 8

8.2.1 Overview ................................................................................................................................................................................. 8

8.2.2 Linking from a PI ............................................................................................................................................................. 8

8.2.3 Linking to a PI ..................................................................................................................................................................... 8

8.2.4 Instance examples using gml:id .......................................................................................................................... 8

8.3 Linking mechanism: UUID ............................................................................................................................................................ 9

8.4 Linking mechanism: URL ............................................................................................................................................................... 9

Annex A (normative) Abstract test suite .......................................................................................................................................................10

Annex B (normative) Encoding using gml:id to link with GML ..............................................................................................11

Annex C (normative) Encoding using gml:id to link with GML application schemas ......................................16

Annex D (normative) Encoding using UUID for linking .................................................................................................................19

Annex E (normative) Encoding using URL for linking .....................................................................................................................21

Annex F (informative) Use case examples ....................................................................................................................................................22

Annex G (informative) RDF examples of linking PIs ..........................................................................................................................27

Bibliography .............................................................................................................................................................................................................................34

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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 on 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 the following

URL: w w w . i s o .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 19155 series can be found on the ISO website.
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Introduction

The Place Identifier (PI) architecture (ISO 19155) defined the conceptual model of a place and

specified normative encodings, for Place Identifiers, not specific to any type of geographic feature. In

this document, three mechanisms are presented that define how Place Identifiers can be linked with

features or objects in other encodings. Even though the identifiers of those features or objects may not

specifically be a place, they may be referred to conceptually as “other identifiers.”

Figure 1 depicts the abstractions of linking mechanisms among feature/object encoding rules.

a) Without the use of a Place Identifier b) With the use of a Place Identifier
Key
encoding rules
linkages
Figure 1 — Linkages with other encoding rules

The linking mechanisms presented in this document are based on accepted information technology

for object identification and reference using gml:id, UUID, or URL. By using these linking mechanisms

with the rules defined here, and according to the type of encoding rule being linked to, Place Identifiers

can more uniformly be related to features and objects — other identifiers — in other encodings.

This extends the functionality of those other identifiers, in different encodings, by linking with Place

Identifiers encoded in GML.

Existing PI data can complement a range of other encodings through the use of the linking mechanisms

defined in this document.

For example, a group of Place Identifiers representing stores in a shopping mall can be associated with

the specific locations inside the shopping mall represented by a GML data set.
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INTERNATIONAL STANDARD ISO 19155-2:2017(E)
Geographic information — Place Identifier (PI)
architecture —
Part 2:
Place Identifier (PI) linking
1 Scope

This document defines the following three mechanisms for linking Place Identifiers (PIs) (see ISO 19155)

to features or objects existing in other encodings:
— Id attribute of a GML object (gml:id) as defined in ISO 19136;
— Universally Unique Identifier (UUID) as defined in IETF RFC 4122;
— Uniform Resource Locator (URL) as defined in IETF RFC 1738.

These PI linking mechanisms are enabled using xlink: href as defined in W3C XML Linking Language

(XLink).

While the identifiers of these features or objects can sometimes identify a place, within the scope of

this document, the identifiers of features or objects existing in other encoding domains are referred to

conceptually as other identifiers.

This document further defines that when PIs are encoded, as specified in ISO 19155, using the

Geography Markup Language (GML) (ISO 19136), they are linked using gml:id to other GML encoded

features. The details of encoding GML instances using gml:id are specified in a normative annex.

Additional normative annexes define encodings for linking Place Identifiers to other identifiers using

UUID and URL and present examples for their use.

This document is applicable to location-based services, linked open data, robotic assisted services

and other application domains that require a relationship between PIs and objects in either the real or

virtual world.

This document is not about creating a registry of Place Identifiers linked to specific features or

objects, and support of linking mechanisms other than gml:id, UUID, and URL is out of the scope of this

document.
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 19103, Geographic information — Conceptual schema language
ISO 19136:2007, Geographic information — Geography Markup Language
ISO 19155:2012, Geographic information — Place Identifier (PI) architecture
IETF, Universally Unique IDentifier (UUID) URN Namespace, RFC 4122, July 2005
IETF, Uniform Resource Locators (URL), RFC 1738, December 1994
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W3C XML Linking Language (XLink) Version 1.1 — Recommendation, 06 May 2010
3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 19155 and the following apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— IEC Electropedia: available at http:// www .electropedia .org/
— ISO Online browsing platform: available at http:// www .iso .org/ obp
3.1
Place Identifier (PI) link

relationship established between PIs and other identifiers in different encoding domains

Note 1 to entry: While the identifiers of these features or objects can sometimes identify a place, within the

scope of this document, the identifiers of features or objects existing in other encoding domains are referred to

conceptually as “other identifiers”.

Note 2 to entry: These “other identifiers” can exist outside of the PI architecture.

3.2
Place Identifier (PI) linking mechanism
means used to define a place identifier (PI) link (3.1)
4 Abbreviated terms
4.1 Abbreviated terms
BIM Building Information Model
CSV comma-separated values
IFC Industry Foundation Class
GUID Globally Unique IDentifier
OGC Open Geospatial Consortium
PI Place Identifier
RDF Resource Description Framework
SVG Scalable Vector Graphics
UML Unified Modeling Language
URI Uniform Resource Identifier
URL Uniform Resource Locator
URN Uniform Resource Name
UUID Universally Unique IDentifier
XML eXtensible Markup Language
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4.2 UML Notation

In this document, conceptual schemas are presented in the Unified Modeling Language (UML). The user

shall refer to ISO 19103 for the specific profile of UML used in this document.
4.3 Backward compatibility

This document uses the concepts defined in the Place Identifier (PI) Architecture (ISO 19155) without

modification. Therefore, no backward compatibility issues exist in this document.

5 Conformance
5.1 General

This document defines three conformance classes, specified in 5.2 to 5.4, matching the requirements

classes of the three linking mechanisms defined in Clause 8. Any PI linking mechanism for which

conformance with this document is claimed shall pass all of the requirements of the abstract test suite

specified in Annex A.
5.2 Linking mechanism: gml:id

PI linking for which gml:id conformance is claimed shall pass all of the requirements specified in the

abstract test suite in A.2.
Table 1 — Conformance class: Linking mechanism: gml:id
Conformance class /conf/19155-2/5/5.2
Dependency A.1
Requirements /req/linking_mechanism/GML_ID
Tests A.2
5.3 Linking mechanism: UUID

PI linking for which UUID conformance is claimed shall pass all of the requirements specified in the

abstract test suite in A.3.
Table 2 — Conformance class: Linking mechanism: UUID
Conformance class /conf/19155-2/5/5.3
Dependency A.1
Requirements /req/linking_mechanism/UUID
Tests A.3
5.4 Linking mechanism: URL

PI linking for which URL conformance is claimed shall pass all of the requirements specified in the

abstract test suite in A.4.
Table 3 — Conformance class: Linking mechanism: URL
Conformance class /conf/19155-2/5/5.4
Dependency A.1
Requirements /req/linking_mechanism/URL
Tests A.4
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6 Place Identifier (PI) concept
6.1 General

A “place” is defined as an identifiable part of any space (ISO 19155), either in the real world or

virtual world.

ISO 19155:2012, 6.1 states that the same place can be identified with multiple Place Identifiers (PIs).

If the place is identified with coordinates, it is called “position” and if the place is identified with

geographic identifiers, it is called “location.” Additionally, the place may be identified with online

resource identifiers such as URI.

In ISO 19109:2015, 7.4, “position” is a spatial attribute of a feature, “location” is a location attribute of a

feature, and a virtual identifier, such as a URI, is a thematic attribute of a feature. Therefore, a PI can be

considered as an attribute of a feature.
6.2 PI structure

Figure 2 shows the structure of the PI, as defined in ISO 19155:2012, 7.2.2. The PI_PlaceIdentifier type

is the basic data type for the PI.
Figure 2 — PI_PlaceIdentifier
The PI_PlaceIdentifier class defines the following attributes.
a) The attribute rs specifies the reference system of the PI.

b) The attribute value is the identifier for a place and is unique within the context of the defined

reference system.

c) The optional attribute validPeriod specifies the period in which the identifier is valid for the place.

The validPeriod can be used to set the expiration of the identifier which can be validated through

implementation. The property of uniqueness of the identifier is determined by the reference system (rs).

7 PI linking
7.1 Overview
There are two main concepts that are standardized in this document.

The first concept is a mechanism for connecting PIs which identify the same place, where the connection

is directly embedded into the PI.

PI matching (ISO 19155:2012, 4.11) is the matching of multiple PIs that represent the same place. This

matching is accomplished through the use of the PI matching service (ISO 19155:2012, 7.3.2) and when

implemented, is performed within the PI architecture. The logical structure of “PI matching” is shown

in ISO 19155:2012, Figure 8, where a “PI_MatchedPISet” connects more than two “PI_PlaceIdentifier”s

which identify the same place. The one way association from “PI_MatchedPISet” to “PI_PlaceIdentifier”

enables users to make links independently with the instances of PI_PlaceIdentifier, and the data

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independence of the connection ensures the use of existing place identifiers because existing data need

not change their schemas.

However, in many situations, relationships exist between PIs encoded using ISO 19155 and other

identifiers in different encodings, existing independently or outside of the PI architecture. As these

other identifiers are usually features or objects in different encodings, it is not possible for them to be

included in or managed by the PI architecture. In these situations, users may want to simply embed the

connection into their PI. Depending on the encodings of these other identifiers, a set of clearly defined

mechanisms is required to expose and use those other identifiers for PI linking.

This is referred to as a Place Identifier (PI) link (3.1), similarly, a Place Identifier (PI) linking mechanism

(3.2) is a means of defining a Place Identifier (PI) link.

While one specific linking mechanism is not suitable for all other identifiers in other encodings,

similarities in linking mechanisms exist, such as the use of XLink for XML-based encodings.

The second concept standardized by this document is the structure of data instances for PI Linking.

This document defines how to use existing constructs to enable linking to PIs without modification to

those encoding rules for object identification and reference.
7.2 PI linking directionality

In this document, all links are directional. In cases where a bi-directional link is required, two distinct

directional links shall be made, one in each direction.

/req/linking_directionality/direction- where a bi-directional link is required, two distinct

al_links directional links shall be made, one in each direction

A combination of directionality and encoding format limits the applicability of this document, as shown

in the following cases:

a) if both identifiers are encoded in GML (ISO 19136:2007), the linking is normative;

b) if one identifier is in another encoding, the linking from a PI to that identifier is normative;

c) if one identifier is in another encoding, the linking from that identifier to a PI is informative.

In Figure 3, the direction of the link between a PI encoded using ISO 19155 and an identifier in another

encoding is shown using an arrow representing the directionality of the link. In addition, normative

linking is shown using a solid line and informative linking is shown using a dashed line.

The normative linking mechanisms are:

a) gml:id: for linking between a PI and another identifier encoded in GML, see 8.2.2 and 8.2.3;

b) UUID or URL: for linking from a PI to an identifier in another encoding, see 8.3 and 8.4, respectively.

Figure 3 depicts linking to PIs from IFC(BIM) and SVG using IfcDocumentReference and rdf: resource

as linking mechanisms. These mechanisms are shown as informative because those encodings are not

being modified by this document.
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Key
encoding rules (examples in this document)
other encoding rules
linking methods (normative)
linking methods (informative)
ISO 19155-2 scope (normative content)
ISO 19155 (normative PI encoding)
Figure 3 — Overview of content in ISO 19155-2
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7.3 PI linking model
The conceptual model in Figure 4 defines the structure of PI linking.

The PI_PlaceIdentifier class defined in this document is an extended data type for the Place Identifier

which enables users to connect a PI directly to other PIs.

The PI_PlaceIdentifier class also has a mandatory association “Linking” in addition to the derived three

attributes. The association “Linking” is a mechanism for connecting PIs which identify the same place,

where the connection is directly embedded into the PI.

NOTE While “PI_MatchedPISet” defined in ISO 19155 has an association to connect more than two “PI_

PlaceIdentifier”s which identify the same place, “PI_PlaceIdentifier” defined in ISO 19155 itself does not have a

property to connect other “PI_PlaceIdentifier”s.
Figure 4 — PI linking model
8 PI linking mechanisms
8.1 Overview

This document defines three mechanisms for linking Place Identifiers to features or objects existing in

other encodings. These PI linking mechanisms are enabled using the following information technologies

for object identification and reference:
— using a gml:id linking both from and to a PI, see 8.2;
— using a Universally Unique Identifier (UUID) linking from a PI, see 8.3;
— using a Uniform Resource Locator (URL) linking from a PI, see 8.4.

When using the linking mechanisms defined in this document, the PIs shall be encoded using ISO 19136,

which is the recommended normative encoding option, as specified in ISO 19155:2012, Annex B.

/req/linking_mechanisms/encoding existing Place Identifiers shall be encoded using ISO 19136

as specified in ISO 19155:2012, Annex B
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Implementation requirements are specified in 8.2, 8.3, and 8.4.

The encodings presented in this document are suitable for linking with a PI but do not represent a

conclusive list and other encodings may also be suitable for linking with a PI using one of the defined

mechanisms. Linkages may also exist directly between multiple encodings and can make use of a PI.

For the purpose of this document, linkages not using a PI are out of scope.
Use case examples of PI linking are presented in Annex F.

The PI architecture and PI linking concepts have implications for use in the semantic web and linked

data. To provide additional descriptions, Annex G includes RDF examples for PIs and PI linking.

8.2 Linking mechanism: gml:id
8.2.1 Overview

If gml:id is used, linking is defined as bi-directional, both from and to a PI, and linking Place Identifiers

with other features encoded in GML and related application schema is specified based on the following

content from ISO 19136:2007, 8.1:

Xlink components are used in GML to implement associations between objects by reference. GML

property elements (ISO 19136:2007, 7.2.3) may carry XLink attributes, which support the encoding of

an association relationship by reference, the name of the property element denoting the target role in

the association.

/req/linking_mechanisms/GML_ID gml:id shall be used when linking to Place Identifiers

encoded in GML
8.2.2 Linking from a PI

An xlink: href property in a PI instance defines a link that shall be used to point to a discrete GML

instance and the value in that discrete GML instance is referenced by traversing the link.

/req/linking_mechanisms/GML_ID/from- the xlink: href property in a PI instance shall use a

a-PI gml:id to define a link that points to a discrete GML
instance
8.2.3 Linking to a PI

The converse is also defined by this document, where an xlink: href property in a GML instance defines

a link that shall be used to point to a discrete PI instance and the value in that discrete PI instance is

referenced by traversing the link.

/req/linking_mechanisms/ GML_ID/to-a-PI the xlink: href property in a GML instance shall use

a gml:id to define a link that points to a discrete PI
instance
8.2.4 Instance examples using gml:id

Examples showing the use of gml:id for linking between PIs and other GML encoded instances are

presented in Annex B.

GML feature instances conforming to application schemas, such as OGC CityGML (OGC 12-019) and OGC

IndoorGML 1.0 (OGC 14-005r3),
...

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