* RDA is focused on seven entities from the FRBR and FRAD models. They fall into two groups: W/E/M/I for describing and identifying resources; and P/F/C for describing and identifying those responsible for various aspects of resources. * The entities are distinct and RDA assigns separate sets of attributes to them. * The entities in the WEMI group are inter-locked when used to describe a single resource. * An Expression must express one and only one Work, and an Item must exemplify one and only one Manifestation. A Manifestation must realize at least one Expression. * The entities in the PFC group have a different relationship. They have a common Agent super-entity. * RDA provides primary or high-level relationships between the entities in the WEMI group, and between WEMI group entities and Agent group entities. These relationships are represented by reciprocal pairs for separate directions to and from each entity.
RDA refines the high-level FR relationships with a rich set of relationship designators between the separate entities. * The high-level relationships lock the WEMI group for a single resource in two parts: Item/Manifestation and Expression/Work. They are linked in both directions to accommodate a manifestation that realizes more than one expression. * Each entity in the WEMI group has a set of high-level relationships with each entity in the Agent group. A work may be created by a Person, Family, or Corporate body,. * And so on. * The function of the Agent group is to provide access to the entities of the WEMI group: the access or authority control function. That requires relationships between the entities with the Agent group. A person can be a member of a family or an employee of a corporate body, and so on. * Access to a specific WEMI entity can also be supported by relationships between WEMI entities for a collection of resources., requiring additions to the set of relationships for a single resource. In particular, relationships between instances of the same entity are needed: a work can be related to another work in many ways, and so on for the other WEMI entities. Access via Agent entities has similar needs. * The diagram now reflects the current “workflow” of RDA descriptive metadata. Starting with the item in hand, the related manifestation, expression(s), and work(s) are described with RDA attributes. The descriptions are then related to associated Agent entities and WEMI entities of other resources to provide access points.
RDA allows us to invert the point of view: from access to item. All relationships have reciprocals, so we can start at any entity and get to an item. * It is the Item that a User is ultimately interested in, the end of the trail. And it is the content of the item that is usually wanted.
Mapping RDA to other namespaces must take into account pure human-readable semantics such as definitions, as well as machine-readable semantics such as property domains and ranges. * This the RDF definition of RDA property P10082. The words in bold are taken from RDA Toolkit. When we look at the BIBFRAME namespace, we find the property cartographicAscensionAndDeclination with an identical RDF comment. This is what the JSC intends by the open license for all RDA vocabularies. The mapping from RDA to BIBFRAME is certainly equivalent from the human-readable semantics. * To compare the machine-readable semantics, we must look at the domains and ranges of the properties. The RDA property has the domain RDA Work class. The BIBFRAME property has domain Cartography class. * Cartography is a sub-class of BIBFRAME Work. * The comparison is therefore between the RDA and BIBFRAME classes labelled “Work”. Are they the same? Their definitions are not very helpful: RDA: A distinct intellectual or artistic creation; BF: Resource reflecting a conceptual essence of the cataloging resource. * If we look at RDA property P20216, the human-readable semantics are again similar. * The BIBFRAME property has domain Cartography. * But the RDA property has domain Expression. * And that does not have a simple hierarchical relationship with RDA Work. * What are we comparing now? It’s getting complicated. * Fortunately, when we look at the ranges, we don’t have any problems. RDA does not specify a range, and BIBFRAME specifies only a literal. * If we ignore domains and ranges, the mapping is easier and obvious. * That is one reason why RDA provides unconstrained properties, with no domains or ranges. * It is true to say, then, that the BIBFRAME properties are sub-properties of the unconstrained RDA properties. We can map BIBFRAME data to non-FRBRized RDA data, but determining a map from FRBR-constrained RDA data to BIBFRAME data will involve further investigation, and probably the need for unconstrained BIBFRAME properties.
The relationships between entities from different data models that focus on essentially the same thing, a bibliographic resource, are not straightforward. * RDA provides relationship properties for the WEMI/IMEW stack – only the direction of the cardinality constraints is shown for clarity. * The ISBD and FRBR Review Groups have agreed to provide properties to relate the single ISBD entity Resource with the FRBR WEMI entities. These were added to the ISBD namespace with “New-proposed” status in 2013. * BIBFRAME provides relationship properties to link BIBFRAME Work and Instance entities. * BIBFRAME also provides a property to “connect Works under FRBR/RDA rules”; that is, to link two BIBFRAME works. * Where does MARC 21 fit in? Can we assume that the domain of MARC is a single entity similar to, if not the same as, ISBD’s Resource? That is certainly the case with UNIMARC. What are the relationships between the BIBFRAME entities and Resource? * What should the relationships between BIBFRAME and RDA entities look like? It seems only necessary to related a BIBFRAME Work to an RDA Expression, because the constraint locks it to a single RDA Work. That is, a BIBFRAME Work is directly related to RDA Expression, not an RDA Work.
RDA, MARC and BIBFRAME: transition and interaction
RDA, MARC and BIBFRAME:
transition and interaction
Presented at LITA/ALCTS MARC Formats
Transition Interest Group seminar, ALA
2014, Las Vegas, 28 June 2014
RDA Entity relationships
pov: Description -> Access
pov: Access -> Item
Relates a work to a system for identifying the location of a celestial
object in the sky covered by the cartographic content of a resource
using the angles of right ascension and declination. (RDA P10082)
rdaw:P10082 (has right ascension and declination)
Relates an expression to the method or system used to represent the
surface of the earth or of a celestial sphere on a plane. (RDA P20216)
rdae:P20216 (has projection of cartographic content)
rdae:P20231 (has work expressed)
Mapping RDA 2 BF
rdau:P60542 (has projection of cartographic content)
rdau:P60346 (has right ascension and declination)