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IFLA Library Reference Model (LRM)



IFLA Library Reference Model (LRM) is a high-level conceptual reference model developed within an entity-relationship modelling framework. It is the consolidation of the separately developed IFLA conceptual models: FRBR, FRAD, FRSAD.




Contents


  • IFLA Library Reference Model (LRM): Videos
  • IFLA Library Reference Model (LRM): Authority Record
  • IFLA Library Reference Model (LRM): Bibliographic Record  
  • IFLA Library Reference Model: A Conceptual Model for Bibliographic Information
  • What is IFLA LRM?
    • IFLA LRM Predecessors
    • What are the principles of IFLA LRM?
    • The Entity-Relationship Model 
    • The Enhanced Entity-Relationship Model
    • (End-)User Tasks as Defined in LRM
    • How is IFLA LRM used?
  • Terminology in IFLA LRM
  • Relationships in IFLA LRM
  • RES and WEMI in IFLA LRM
  • Agent in IFLA LRM
  • Place and Time Span in IFLA LRM





Note: This article is chiefly drawn from the presentations available on the Library of Congress website² and the IFLA Library Reference Model (LRM)¹. 







IFLA LIBRARY REFERENCE MODEL (LRM): VIDEOS

Videos about the Library Reference Model of IFLA and its impact on the new RDA: Resource Description and Access, cataloging standard.


Video 1

Title: Chris Oliver LRM presentation June 2018

Summary: Chris Oliver describes the new Library Reference Model and how it builds upon the foundation established by FRBR.

Creator: RDA Toolkit

Original Published Date: August 23, 2018

Runtime: 29  minutes



Video 2

Title: LRM and RDA : overview of the 3R Project (Gordon Dunsire)

Summary: This presentation is from "The redesigned RDA Toolkit: what you need to know to get ready", an event held on October 22, 2018 at Auditorium of the Grande Bibliothèque, Bibliothèque et Archives nationales du Québec, Montréal (Québec). Gordon Dunsire is the Chair of the RDA Steering Committee.

Creator: RDA Toolkit

Original Published Date: Nov 8, 2018

Runtime: 67 minutes



Video 3

Title: 2018 12 05 The IFLA LRM Model

Summary: An ALCTS webinar.

Creator: ALCTS

Original Published Date: May 22, 2019

Runtime: 59 minutes



Video 4

Title: A deeper dive into Nomen and appellations

Summary: Presentation by Gordon Dunsire, RDA Technical Team Liaison Officer,, at "A Deeper Dive Into RDA", held on Monday, January 28, ALA Midwinter Meeting 2019 in Seattle, Washington.

Creator: RDA Toolkit

Original Published Date: Feb 5, 2019

Runtime: 27 minutes



Video 5

Title: Anticipating the New RDA

Summary: The RDA Toolkit Restructure and Redesign Project (3R Project) was announced in 2017 to improve the usability of the Toolkit and to address a range of cataloging issues, including the implementation of the IFLA Library Reference Model (LRM). This presentation discusses some of the important updates to RDA that will be incorporated when the 3R Project is complete. There will be a brief look at new concepts introduced by the LRM, and their impact on current RDA content.  Chris Oliver describes the new Library Reference Model and how it builds upon the foundation established by FRBR.

Creator: Library of Congress

Original Published Date: Nov 26, 2019

Runtime: 67  minutes








IFLA LIBRARY REFERENCE MODEL (LRM): AUTHORITY RECORD

It is to be noted that "IFLA Library Reference Model" has been established as a heading in the Library of Congress Subject Headings (LCSH).

1. Authority Record of IFLA Library Reference Model (LRM), from the Library of Congress Authorities¹.

Authority Record of IFLA Library Reference Model (LRM)


2. Authority Record of IFLA Library Reference Model (LRM), from the Library of Congress Linked Data Service².

Authority Record of IFLA Library Reference Model (LRM)








IFLA LIBRARY REFERENCE MODEL (LRM): BIBLIOGRAPHIC RECORD

Catalog record of the book:
BIBLIOGRAPHIC RECORD FOR THE WORK: IFLA LIBRARY REFERENCE MODEL (LRM)
BIBLIOGRAPHIC RECORD FOR THE WORK: IFLA LIBRARY REFERENCE MODEL (LRM)
BIBLIOGRAPHIC RECORD FOR THE WORK: IFLA LIBRARY REFERENCE MODEL (LRM)








IFLA Library Reference Model (LRM)








IFLA LIBRARY REFERENCE MODEL: A CONCEPTUAL MODEL FOR BIBLIOGRAPHIC INFORMATION


Source: The presentation shown below is created by Pat Riva, Patrick Le Bœuf, and Maja Žumer and is available from IFLA¹. This document comes with a Creative Commons license.
.








WHAT IS IFLA LRM?

Source: The description which is given below is created by the Standing Committee on Training Program for Cooperative Cataloging (PCC) and is available from the Library of Congress².

A high-level conceptual reference model developed within an entity-relationship modelling framework. It is the consolidation of the separately developed IFLA conceptual models: FRBR, FRAD, FRSAD.

  • IFLA-LRM is a high-level conceptual reference model developed with an enhanced entity-relationship modelling framework covering bibliographic data. 
  • IFLA-LRM is built on an entity-relationship model that incorporates the notion of inheritance of attributes and relationships from an entity to all the entities that are subsumed in it.
  • IFLA-LRM aims to make explicit general principles governing the logical structure of bibliographic information, without making presuppositions about how that data might be stored in any particular system or application.
  • IFLA-LRM bases its functional scope based on user tasks—Find, Identify, Select, Obtain, Explore.
  • IFLA-LRM is intended as a guide or basis on which to formulate cataloging rules and implement bibliographic system.


IFLA LRM Predecessors

  • Functional Requirements for Bibliographic Records (FRBR): is a conceptual entity-relationship model of metadata developed by IFLA for information objects. Published in 1998 by IFLA
  • Functional Requirements for Authority Data (FRAD): defines functional requirements of authority records. FRAD was developed as an extension and expansion of FRBR. Approved 2009 by IFLA
  • Functional Requirements for Subject Authority Data (FRSAD): conceptual entity-relationship model and a continuation of the work based upon the FRBR model. The main focus is how: “... entities that serve as subject of intellectual or artistic endeavor” can be related and controlled within the bibliographic universe. Approved 2010

IFLA Library Reference Model (LRM) combines and consolidates the FR family into a single coherent model.


What are the principles of IFLA LRM?

  • A high-level conceptual reference model developed with an enhanced entity-relationship modelling framework, covering bibliographic data in a broad, general sense.
  • Aims to make explicit general principles governing the logical structure of bibliographic information, without making presuppositions about how that data might be stored in any particular system or application.
    • does not make a distinction between data traditionally held separately as bibliographic, authority, or holdings data; includes it all.
  • Takes its functional scope from the user tasks, defined from the point-of-view of the end-user and the end-user’s needs.


The Entity-Relationship Model 

  • Describes interrelated things of interest in a specific domain of knowledge
  • Composed of:
    • Entities—classify things of interest
    • Relationships—relationships that can exist between entities 

    • Attributes—further describe an entity or relationship in some way



The Enhanced Entity-Relationship Model

  • Entity-relationship model that incorporates the notion of inheritance of attributes and relationships from an entity to all the entities that are subsumed in it



Example: A Person is a subclass of an Agent. It thus inherits the attributes and relationships of the Agent class, while also having its own unique attributes and properties


(End-)User Tasks as Defined in LRM

  • Find: To bring together information about one or more resources of interest by searching on any relevant criteria
  • Identify: To clearly understand the nature of the resources found and to distinguish between similar resources
  • Select: To determine the suitability of the resources found, and to be enabled to either accept or reject specific resources
  • Obtain: To access the content of the resource
  • Explore: To discover resources using the relationships between them and thus place the resources in a context


How is IFLA LRM used?

  • LRM is intended as a guide or basis on which to formulate cataloging rules and implement bibliographic system
  • The new version of RDA is a set of cataloging guidelines based on LRM




TERMINOLOGY IN IFLA LRM

Source: The description which is given below is created by the Standing Committee on Training Program for Cooperative Cataloging (PCC) and is available from the Library of Congress².

  • All definitions (except Inheritance) taken from LRM Chapter 7, Glossary of Modelling Terminology
  • Vocabulary mostly originates from the entity-relationship model
  • Some vocabulary familiar from FRBR, but be cautious—it may be somewhat differently defined

Terminology Covered here are given below:
  • Class
  • Entity
  • Superclass
  • Subclass
  • Disjointedness
  • Property
  • Attribute
  • Relationship
  • Inheritance
  • Domain
  • Range
  • Reification


Class

  • LRM gives no formal definition for class, although the term is used often
  • Here are some definitions from common usage and from the RDF schema:
    • “A group, set, or kind, sharing common attributes” (Merriam-Webster)
    • “Resources may be divided into groups called classes. The members of a class are known as members of the class” (RDF Schema 1.1)
  • The class concept is inherent to the enhanced entity-relationship model, but not part of a basic entity-relationship model


Entity

An abstract class of conceptual objects, representing the key objects of interest in the model

… that is, “the key objects of interest to users of library information systems.” (LRM 4.1.1.)


  • Entities are treated as classes in LRM; the term entity tends to be used mostly for the LRM entities, while class is used for non-RDA entities and descriptions of LRM entities. Other Modules will define and explain specific LRM entities.
  • The primary benefit of treating entities as classes is that it also introduces the relational concepts of superclass and subclass


Class relationships--Superclass

An entity may group several entities/classes together in a superordinate class, a more general class under which a set of more specific classes is incorporated. This is known in LRM as a superclass.




Example: The entity Agent is the superclass of the entities Person and Collective Agent


Class relationships--Subclass

Multiple entities may be grouped into a superordinate entity, if all their instances are instances of that larger entity. This is known as a subclass. The LRM definition is:

“An entity, all of whose instances are also instances of a larger, superordinate entity.”

The relationship is described as an “isA” relationship



Example: The entities Person (an individual) and Collective Agent (a group) are subclasses of the entity Agent. 

Person “isA” Agent Collective Agent “isA” Agent


Entity Hierarchy: Superclass, Class, Subclass




Disjoint Entities

Entirely non-overlapping sets.  Disjoint entities can have no instance that is simultaneously an instance of more than one of these entities

“IFLA LRM declares that, other than those entities related by the “isA” hierarchies, the entities in the model are disjoint.”  (IFLA LRM (2017-12) 5.2)





Disjointness is easy!

Some examples of disjointness are easily understandable.

For example, something cannot be both an instance of the person entity and an instance of the collective agent entity.


These entities have an “isA” relationship to the entity agent, but they are disjoint to each other.



Maybe not always easy.

Disjointness is less obvious but equally important when something is considered in different aspects.



For example: Hamlet as work, expression, manifestation, and item: all may share the same nomen string (can be referred to by the same name) but are nonetheless different and disjoint entities


Property, Attribute, Relationship

Property: An attribute or relationship of an entity

Attribute: A type of data which characterizes specific instances of an entity


Relationship: A connection between instances of entities




Inheritance

Definition: Modeling in which an entity or class automatically acquires all the attributes and relationships from its superclass. 

Example:

The Agent entity has the following attributes:
    • Contact information [LRM-E6-A1]
    • Field of activity [LRM-E6-A2]
    • Language [LRM-E6-A3]

The Person entity “inherits” these attributes and adds the following attribute:
  • Profession/Occupation [LRM-E7-A1]


Properties--Inheritance

Any property (relationship or attribute) that applies to a superclass also applies to all entities of its subclasses
  • Example: Any relationship or attribute that applies to the entity Agent also applies to the entity Person (a subclass of Agent), and therefore does not need to be specifically declared for Person
    • The entity Agent has the attribute Language, defined as “A language used by the agent when creating an expression.” The entity Person is a subclass of the entity Agent and therefore also has the attribute Language
    • The relationship “is member of” is defined for the entity Agent.  It also applies to the entity Person, which is a subclass of the entity Agent


Relationships--Domain & Range

Domain:  The source entity, or departure point, for a relationship

Range:  The target entity, or arrival point, for a relationship

To use a grammatical analogy, Domain and Range can be thought of as the subject and object, respectively, of a relationship.





Domain & Range

For example:

In the relationship “Work ‘is realized through’ Expression,” Work is the domain and Expression is the range.




In the inverse relationship “Expression ‘realizes’ Work,” Expression is the domain and Work is the range.





Reification
  • Process through which a relationship is modelled as an entity, so that it can in turn have its own attributes and relationships
In non-technical English, to reify is “To regard or treat (an abstraction) as if it had concrete or material existence.  [Latin rēs, rē-, thing … + fy.]  (American Heritage Dictionary, third edition.)
Reification in LRM is just a specialized instance of this.  Relationships are not entities in LRM, but treating them as if they were allows them to be more fully described and discussed (as in Table 4.7 and the detailed definition in 4.3.3).






RELATIONSHIPS IN IFLA LRM

Source: The description which is given below is created by the Standing Committee on Training Program for Cooperative Cataloging (PCC) and is available from the Library of Congress².


At the end of this module, you will be able to:

  • Define key vocabulary terms associated with relationships
  • Understand basic principles of relationships
  • Interpret entity-relationship diagrams
  • Identify relationships defined in IFLA LRM


What are relationships?

  • An essential part of the bibliographic universe
  • Connect instances of entities and provide context for them
  • In entity-relationship models, like IFLA LRM, the entities define the framework of the model and function as nodes, while relationships connect entities to each other




Domain and Range

Entities serve as domains and ranges of relationships

Domain:

  • The source entity, or departure point, for a relationship
  • The domain is the first entity mentioned in a relationship


Range:
  • The target entity, or arrival point, for a relationship
  • The range is the second entity mentioned in a relationship

=================
WORK [domain]


is realized through


EXPRESSION [range]

=================



Inverse (Reciprocal) Relationships

  • In inverse relationships the entity that served as the domain becomes the range, the entity that served as the range becomes the domain, and the inverse name of the relationship is used
  • In IFLA LRM, inverse relationships can be referred to by the number of the relationship plus the suffix “i”




Recursive and Symmetric Relationships

Recursive:
  • A relationship for which the same entity serves as both domain and range
(LRM-R18) WORK has part WORK
(LRM-R18i) WORK is part of WORK



Symmetric:

  • A relationship for which the relationship name is the same as the name of the inverse relationship

(LRM-R1) RES is associated with RES
(LRM-R1i) RES is associated with RES






Relationship Names


  • Relationships that express states or ongoing activities are named in the present tense

PLACE is associated with RES
AGENT is member of COLLECTIVE AGENT 
RES is subject of WORK


  • Relationships that express actions that were logically completed in the past are named in the past tense

WORK was created by AGENT
AGENT created EXPRESSION
NOMEN was assigned by AGENT



Cardinality

  • Cardinality specifies the number of instances of the domain and range entities that may be connected by the specific relationship.
  • 1 to M (one to many):
            WORK is realized through EXPRESSION
    • Each work has one or more expressions that realize it.
    • Each expression realizes exactly one work.
  • M to M (many to many):
            WORK was created by AGENT
    • Any agent may create many works.
    • A work may be created by many agents.



Entity-Relationship Diagrams

  • Summarize the entities and the significant relationships between them






Relationships in IFLA LRM

  • 36 general relationships are declared in IFLA LRM.
  • Implementations of IFLA LRM, such as RDA, may include refinements of the relationships declared in IFLA LRM in a consistent and coherent way.




RES is associated with RES (LRM-R1)

  • The top-level, general relationship


  • Refinements:
    • All other relationships declared in IFLA LRM are specific refinements of this relationship.
      • The refinements add to the semantic content of the specific association between particular domain and range entities, and specify stricter constraints when appropriate.
    • In implementations of IFLA LRM, such as RDA, any additional relationships that are needed can be defined as refinements of the additional relationships defined in IFLA LRM or this top relationship.




Core Relationships


  • In IFLA LRM, the relationships between works, expressions, manifestations, and items are core.





  • Other relationships are encouraged because they enable exploration and discovery and are very important for end-users.


Entity Hierarchy

  • Res
    • Work
    • Expression
    • Manifestation
    • Item
    • Agent
      • Person
      • Collective Agent
    • Nomen
    • Place
    • Time-span

  • The single top-level entity in IFLA LRM is res; all other entities are direct or indirect subclasses of res.

  • The eight direct subclasses of res are: work, expression, manifestation, item, agent, nomen, place, and time-span.

  • Agent is a superclass entity with two subclasses: person and collective agent.



isA Hierarchy

  • When one entity is declared a superclass of other entities, the other entities have a subclass relationship to the superclass. This relationship between the subclass and superclass can be expressed as “is a” (or isA).




  • Any relationship or attribute that applies to the superclass also applies to the subclass without being explicitly declared. The reverse direction is not true; relationships or attributes explicitly defined for the subclass do not apply to the whole superclass.






Overview of IFLA LRM Relationships

  • The next image contains an overview diagram of almost all relationships defined in IFLA LRM.
  • To simplify the presentation, the following are not shown:
    • Shortcuts
    • The “isA” hierarchy that connects all entities to the superclass entity res
    • Inverse (reciprocal) relationships
    • Cardinality
  • The arrow represents the direction of the relationship only and the relationship name corresponds with that direction.


IFLA Library Reference Model (LRM)
Image source: IFLA LRM document¹





Compound or Multi-Step Relationships

  • Relationships declared in IFLA LRM can serve as building blocks for “compound” or multi-step relationships.
  • Traversing two or more relationships is referred to as a “path”.


(LRM-R12) WORK has as subject RES +

(LRM-R13) RES has appellation NOMEN

[The link between a work and a term used to represent its subject is provided by a two-step path which also accounts for the role of the entity res.]





Shortcut Relationships


  • When a particular path is frequently required in a particular application, such as RDA, it can be implemented as a single relationship which serves as a shortcut for the more developed path.
  • The intermediate entities become implicit.


(LRM-R15) NOMEN is equivalent to NOMEN



Is the same as the pair of relationships:

(LRM-R13i) NOMEN1 is appellation of RES +

(LRM-R13) RES has appellation NOMEN2




Relationship Paths with isA

  • The entity subclass/superclass structure (the “isA” hierarchy) can be used to restrict the domain or range entities in a relationship.


(isA) PERSON isA AGENT +

(LRM-R5i) AGENT created WORK

[IFLA LRM has declared the relationship between the entities agent and work.

The “isA” hierarchy is used to specify the agent is a person.]



The above pair of relationships implies the shortcut relationship:

PERSON created WORK



Relationship Paths with isA


  • Multi-step paths can make use of both the “isA” hierarchy and the relationships declared in the model.


(LRM-R5) WORK was created by AGENT1 +
(isA) AGENT1 isA RES +
(LRM-R13) RES has appellation NOMEN +
(LRM-R14i) NOMEN was assigned by AGENT2

[The path linking a work to a nomen assigned by one agent (such as a bibliographic agency) with the agent responsible for creating the work. For example, “The Color Purple” (work) was created by Alice Walker (agent) who is referred to by an access point (nomen) assigned by the Library of Congress (agent).]




Summary

  • Relationships connect entities to each other.
  • The domain is the source entity while the range is the target entity of a relationship.
  • The 36 relationships declared in IFLA LRM are general but may be refined in implementations, such as RDA.
  • The core relationships in IFLA LRM exist between works, expressions, manifestations, and items.
  • The “isA” hierarchy is used to express a relationship between a subclass and its superclass.
  • Relationships that apply to the superclass also apply to the subclass.
  • In implementations, shortcuts may be defined for frequent multi-step relationships.









RES AND WEMI IN IFLA LRM


Source: The description which is given below is created by the Standing Committee on Training Program for Cooperative Cataloging (PCC) and is available from the Library of Congress².



Res (Top Entity)

Any entity in the universe of discourse. Res (“thing” in Latin) is the top entity in the IFLA LRM. Res includes both material or physical things and concepts. Everything considered relevant to the bibliographic universe, which is the universe of discourse in this case, is included. Res is a superclass of all the other entities that are explicitly defined, as well as of any other entities not specifically labelled.

  • Res is defined as “any entity in the universe of discourse.” It is the top entity in IFLA LRM
  • The RDA Entity is a subclass of Res (but outside of LRM) that includes “key conceptual objects in the universe of human discourse that is a focus of interest to users of RDA metadata in a system for resource discovery.”
  • WEMI entities have their origins in FRBR, but definitions are clarified and updated for LRM 
  • WEMI entities are disjoint from one another



What can a Res be?

  • People
  • Animals
  • Works
  • Places
  • Abstract ideas (e.g., empathy)
  • Time periods
  • Identities
  • Spirits
  • Unreal things
  • <anything else!>



RDA Entity
  • A subclass of Res (outside of LRM) that is the top entity in RDA
  • Definition: An abstract class of key conceptual objects in the universe of human discourse that is a focus of interest to users of RDA metadata in a system for resource discovery.



What can an RDA Entity be?
  • Agent Entity
  • Collective Agent Entity
  • Corporate Body Entity
  • Family Entity
  • Person Entity
  • Work Entity
  • Expression Entity
  • Manifestation Entity
  • Item Entity
  • Nomen Entity
  • Place Entity
  • Timespan Entity


Bringing clarity

As LRM consolidated entities from FRBR, it added clarification and updates to existing definitions for Work, Expression, Manifestation, and Item. 



Work Entity


Work Entity in FRBR

The first entity defined in the model is work: a distinct intellectual or artistic creation.

A work is an abstract entity; there is no single material object one can point to as the work.

We recognize the work through individual realizations or expressions of the work, but the work itself exists only in the commonality of content between and among the various expressions of the work.


Work Entity in IFLA LRM

The intellectual or artistic content of a distinct creation.

A work is an abstract entity that permits the grouping of expressions that are considered functional equivalents or near equivalents. A work is a conceptual object, no single material object can be identified as the work.

The essence of the work is the constellation of concepts and ideas that form the shared content of what we define to be expressions of the same work. A work is perceived through the identification of the commonality of content between and among various expressions. However, similarity of factual or thematic content alone is not enough to group several expressions as realizing the same instance of work


Source: The presentation shown below is created by the Standing Committee on Training Program for Cooperative Cataloging (PCC) and is available from the Library of Congress².






AGENT IN IFLA LRM

Source: The presentation shown below is created by the Standing Committee on Training Program for Cooperative Cataloging (PCC) and is available from the Library of Congress².





PLACE AND TIME SPAN IN IFLA LRM

Source: The presentation shown below is created by the Standing Committee on Training Program for Cooperative Cataloging (PCC) and is available from the Library of Congress².











USED FOR
  • FRBR-Library Reference Model
  • FRBR-LRM (Conceptual model)
  • International Federation of Library Associations and Institutions Library Reference Model
  • Library Reference Model, IFLA




REFERENCES

1. Riva, Pat, et al., "IFLA Library Reference Model: a conceptual model for bibliographic information," International Federation of Library Associations and Institutions, August 2017; amended and corrected December 2017. https://www.ifla.org/files/assets/cataloguing/frbr-lrm/ifla-lrm-august-2017_rev201712.pdf (accessed April 23, 2020).

2. Library of Congress, "Preparing for the New RDA: RDA Toolkit Restructure and Redesign Project (3R Project)," https://www.loc.gov/catworkshop/RDA2020/index.html (accessed April 23, 2020).

3. Library of Congress, "IFLA Library Reference Model," https://authorities.loc.gov/cgi-bin/Pwebrecon.cgi?AuthRecID=10630644&v1=1&HC=1&SEQ=20200423010113&PID=6ZFvaDDbB5QZ3qqz-idX61-3QC7 (accessed April 23, 2020).

4. Library of Congress, "IFLA Library Reference Model," http://id.loc.gov/authorities/subjects/sh2017004509.html (accessed April 23, 2020).

5. Maja Žumer; edited by Birger Hjørland and Claudio Gnoli; ISKO, "IFLA Library Reference Model (LRM): Harmonisation of the FRBR Family," https://www.isko.org/cyclo/lrm (accessed April 23, 2020).






SEE ALSO


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