**5. Conclusion**

*Linked Open Data - Applications, Trends and Future Developments*

namespace or to link to resources outside the initiative.

potential for interoperability [2].

frameworks such as FRBR.

another, but different, silo.

its own controlled vocabularies and ontologies versus relying on others to do so. Ontologies suitable for the Linked Data environment are taxonomies and thesauri that meet the W3C Web Ontology Language (OWL) standard [22]. For example, the Library of Congress Subject Headings modeled in the Simple Knowledge Organization System (SKOS) framework is an OWL-compliant ontology.

The existence of high-quality, stable ontologies is particularly a relevant concern with regard to the use and reuse of Linked Open Data resources. For instance, as one researcher notes, many LOD ontologies and vocabularies are developed in the context of research projects, which means that for a particular moment they may be up-to-date, accurate, and in compliance with current standards, though it does not ensure continued governance and maintenance [12]. Thus, the reliance on such vocabularies could present the threat of obsolescence should governing bodies discontinue their activities. Thus, it appears that BIBFRAME will need to assess the stability of ontologies and vocabularies, such as those for resource type, and determine if it is better to develop and maintain its own within the BIBFRAME

Secondly, although BIBFRAME claims that the model should be interoperable with any serialization using triples and URIs, the fact that the initiative has serialized the model in RDF/XML may be a limitation. In other words, because the initiative has limited its serialization within a single framework, it may discourage implementation in other formats. As one researcher notes, it may be better for the initiative to provide potential implementers with examples from a number of possible serializations in order to demonstrate the model's flexibility, extensibility, and

Thirdly, there may be difficulties with viably implementing the BIBFRAME model which are rooted in the nature of RDF itself. As the study in [19] notes in their comparison of BIBFRAME, FRBR, and RDA, there is nothing in RDF that prevents people from making nonsensical RDF triples. In other words, there are no validation mechanisms for the creation of RDF statements, as there are for wellformed XML or HTML documents. While, as the researchers note, BIBFRAME has proposed the use of profiles in order to establish content rules and constraints on the creation of BIBFRAME records, these do not prevent potential difficulties with the integration of BIBFRAME data elements with data elements modeled in other

However, perhaps the biggest threat to BIBFRAME as a mechanism to expose library data in a Semantic Web friendly way lies in the fact that, like the framework itself, the Semantic Web is still under development. For instance, as has been noted in the literature, understanding of what actually constitutes Linked Data is still under debate [19]. Since the very underpinning of the Semantic Web is still in flux, there is a possibility that any operationalization of the concept will change in the future. Thus, if the current methods for creating Linked Data alter significantly in the future, and if data described with current methods cannot be easily translated into the newer modes, then BIBFRAME Linked Data could potentially become obsolete, resulting in the relegation of library data to yet

This final point may also be exacerbated by the very fact that BIBFRAME is a model for the description of bibliographic data within the library community itself. For instance, as some researchers have noted, for data to be truly integrated in the Web, what is required is a common model for data description that includes not only bibliographic data but data of all types [2]. In other words, BIBFRAME, as a model for the description of bibliographic data, may not be intuitively understood by others outside the library community, which may result in a lack of implementation and difficulties with the integration of data embedded in other frameworks.

**14**

It is the intention of the BIBFRAME initiative to design the model in such a way that it not only can serve as the standard encoding and interchange format of bibliographic data within the library community but also be a model for integrating library data within the Web environment more generally. As such, the BIBFRAME model is designed with a high degree of flexibility that can accommodate any number of existing models as well as models yet to be developed within the Web environment. The model's flexibility is intended to foster extensibility.

However, regarding the model itself, there appears to be a significant need to consider the creation of a super-entity that would encapsulate the work and instance entities. With regard to the cataloging requirements for the description of complex resources such as audiovisual materials and serial publications, the creation of such a super-entity would solve a number of bibliographic description challenges. The existence of a super-entity would permit the description of resources and relationships that are currently difficult to model within the existing framework. Resources that do exhibit intellectual content or that are primarily event based would be easier to depict if such a super-entity was present.

BIBFRAME attempts to be content standard and model agnostic. Its framework is intended to be flexible enough to accommodate existing models. While increasing its extensibility, the framework may also result in an uncertainty of its application in specific cataloging contexts. This too may limit the willingness of the library community to invest in its adoption. Furthermore, even though BIBFRAME's potential for extensibility is intended to foster its adoption in a wide range of bibliographic contexts and to work equally well for divergent descriptive needs, its ability to accommodate most if not all modeling and content standards currently in use or yet to be invented may be optimistic. In this regard, BIBFRAME's ability to support widespread interoperability needs to be further addressed.

In this study we discussed the relationship of BIBFRAME to the prevailing content standards and models employed by cultural heritage institutions in order to determine the degree, to which BIBFRAME can be a viable and extensible framework for bibliographic description and exchange in the Web environment. Despite the promise of improved data management, sharing, and usage offered through the BIBFRAME model, there are various challenges that must be overcome for its adoption within the library community. However, if the initiative can overcome what will likely be significant challenges to the implementation of the model, BIBFRAME appears to be poised to become the next standard of bibliographic description and exchange for the library community and beyond. Furthermore, the model also promises to make library data more visible on the Web, not only to the benefit of users looking for library resources but also for reuse in contexts outside of the library community. Finally, it appears that BIBFRAME will permit the full description of relationships between and among resources, enhancing and enriching the user experience of library information.

*Linked Open Data - Applications, Trends and Future Developments*
