Definition of Object-Oriented frbr

3. FRBR_ER Family to FRBR_OO Mappings

3.1. Introduction

This chapter defines the mapping between the FRBR_ER model (Functional Requirements for Bibliographic Records http://www.ifla.org/files/cataloguing/frbr/frbr_2008.pdf) and FRBR_OO (FRBR object-oriented definition and mapping of the FRBR_ER). The mapping includes a listing of the entities, relationships and attributes defined in FRBR_ER and shows how the same information can be expressed using FRBR_OO. These mappings can be seen on one hand as an intellectual definition of the relationship between both models. On the other hand, they are in a format that could be turned more or less mechanically into an algorithm to automatically transform data structured following the one form into data in the other form, i.e. they can be used to implement an automatic data translation.

The FRBR_OO model includes a more elaborated set of classes and for this reason there are several FRBR_OO classes listed for some of the FRBR_ER entities.
FRBR_OO is defined as an extension to the CIDOC CRM model which regards any information element as a property (or relationship) between two classes. For this reason each FRBR attribute or relationship is defined using a path of subsequent properties of FRBR_OO that includes the domain, the property name and the range of each property in the path.
The attributes in FRBR_ER have been defined at a logical level and express the characteristics of an entity as they might be viewed and composed by a user when creating an information system. In contrast to that, FRBR_OO tries to model the things and processes of the reality that librarians deal with and that FRBR_ER entities refer to explicitly or implicitly. Therefore corresponding paths expressed using FRBR_OO are in many cases complex paths that include the intermediate classes and properties that are needed to make explicit the implicit meaning and structure of the FRBR attributes. Using the same method of mapping, FRBR_OO can also be used to describe the meaning of data structures and models other than FRBR and so give an account of the degree to which such data structures or models represent library concepts.
Some FRBR_ER attributes and relationships will correspond to more than one path in FRBR_OO depending on the interpretation and use of an attribute or a relationship. This is particularly evident when inspecting manifestation attributes where attributes can be mapped to one path if they are used for uncontrolled text entries and a different path if they are used for codes or terms from a controlled set of values.

3.2. Explanation of Types Used in the Mapping

FRBR_OO is a core ontology in the sense of the CIDOC CRM, i.e., it specifies only the concepts necessary to describe the basic relationships between things in the selected domain of discourse. The same holds for the FRBR_ER model. Therefore, FRBR_OO adopts the CRM model’s use of external types, i.e. terms that appear as data, declared as instances of the class E55 Type, to declare specialisations of concepts or relationships that are considered not to contribute to basic structure of the core ontology.
Some of the FRBR_ER attributes and relationships are considered to be too specific in this sense and for this reason are expressed in the mapping using paths that include instantiation of E55 Type in different ways. The following summary lists the different ways external types are used in the mapping. The listing of types is not exhaustive but is included as examples for the types (terms) that are needed here and there to express all the semantics of bibliographic data elements in FRBR_OO. Quotation marks indicate type values (instances of E55 Type) whereas type names without quotation marks identify whole type vocabularies.
FRBR_ER attributes mapped to FRBR_OO using P3 has note in combination with P3.1 has type.

This solution is used to map data elements that are uncontrolled text entries. They are all mapped to the property P3 has note for the respective class. In the sequence, P3.1 has type is used to differentiate between different special meanings of the P3 has note property and to express the particular meaning of the note, such as:

• 
  P3.1 has type: E55 Type = {“Capture mode”, “Collation”, “Colour”, “Extent of the carrier”, “File characteristics”, “Foliation”, “Generation”, “Groove width”, “Kind of cutting”, “Kind of sound”, “Physical medium”, “Playing speed”, “Presentation format”, “Reduction ratio”, “Reproduction characteristics”, “Scheduled treatment”, “Series statement”, “System requirements”, “Tape configuration”, “Technique”, “Type size”, “Typeface”,…}
  

FRBR_ER attributes mapped to FRBR_OO using P2 has type.

This solution is used for data elements that are coded values or terms from a controlled vocabulary and express categorical characteristics of an entity. In the sequence, the use of the respective terminology to instantiate E55 Type should be restricted to specific vocabularies as indicated in the following list:

• 
  E55 Type = superclass of (Capture mode, Colour, File characteristics, Foliation, Form of carrier, Generation, Groove width, Kind of cutting, Kind of sound, Playing speed, Presentation format, Reduction Ratio, Reproduction characteristics, System requirements, Tape configuration, Type size, Typeface,…)
  

FRBR_ER attributes mapped to FRBR_OO using P148 has component (is component of)of E33 Linguistic Object P2 has type.

This solution is used for data elements that are transcribing information appearing in the content of a bibliographic object, typically the title page. The property P2 has type E55 Type is used to define the category for this information, such as:

• 
  E55 Type = {“Edition/Issue designation”, “Series statement”, “Statement of responsibility”}
  

FRBR_ER relationships mapped to FRBR_OO using R2 is derivative of in combination with R2.1 has type.

This solution is used to parametrise the specialisations of the more generic FRBR_OO property R2 is derivative of by the corresponding FRBR_ER subproperties:

• 
  R2.1 has type E55 Type = {“Abridgement”, “Adaptation”, “Arrangement”, “Imitation”, “Revision”, “Summary”, “Transformation”, “Translation”}