Online Computer Library Center

© 1998 Eric Miller The Resource Description Framework (RDF) is an infrastructure that enables the encoding, exchange and reuse of structured metadata. RDF is an application of XML that imposes needed structural constraints to provide unambiguous methods of expressing semantics. RDF additionally provides a means for publishing both human-readable and machine-processable vocabularies designed to encourage the reuse and extension of metadata semantics among disparate information communities. The structural constraints RDF imposes to support the consistent encoding and exchange of standardized metadata provides for the interchangeability of separate packages of metadata defined by different resource description communities. The World Wide Web affords unprecedented access to globally distributed information. Metadata, or structured data about data, improves discovery of and access to such information. The effective use of metadata among applications, however, requires common conventions about semantics, syntax and structure. Individual resource description communities define the semantics, or meaning, of metadata that address their particular needs. Syntax, the systematic arrangement of data elements for machine-processing, facilitates the exchange and use of metadata among multiple applications. Structure can be thought of as a formal constraint on the syntax for the consistent representation of semantics. The Resource Description Framework (RDF), developed under the auspices of the World Wide Web Consortium [W3C], is an infrastructure that enables the encoding, exchange and reuse of structured metadata. This infrastructure enables metadata interoperability through the design of mechanisms that support common conventions of semantics, syntax and structure. RDF does not stipulate semantics for each resource description community, but rather provides the ability for these communities to define metadata elements as needed. RDF uses XML (eXtensible Markup Language) as a common syntax for the exchange and processing of metadata. The XML syntax is a subset of the international text processing standard SGML (Standard Generalized Markup Language) [SGML] specifically intended for use on the Web. The XML syntax provides vendor independence, user extensibility, validation, human readability and the ability to represent complex structures. By exploiting the features of XML, RDF imposes structure that provides for the unambiguous expression of semantics and, as such, enables consistent encoding, exchange and machine-processing of standardized metadata. RDF supports the use of conventions that will facilitate modular interoperability among separate metadata element sets. These conventions include standard mechanisms for representing semantics that are grounded in a simple, yet powerful, data model discussed below. RDF additionally provides a means for publishing both human-readable and machine-processable vocabularies. Vocabularies are the set of properties, or metadata elements, defined by resource description communities. The ability to standardize the declaration of vocabularies is anticipated to encourage the reuse and extension of semantics among disparate information communities. For example, the Dublin Core Initiative [DC], an international resource description community focusing on simple resource description for discovery, has adopted RDF [DCRDF]. Educom's IMS Instructional Metadata System [IMS], designed to provide access to educational materials, has adopted the Dublin Core and corresponding architecture and extended it with domain-specific semantics. RDF is designed to support this type of semantic modularity by creating an infrastructure that supports the combination of distributed attribute registries. Thus, a central registry is not required. This permits communities to declare vocabularies which may be reused, extended and/or refined to address application or domain specific descriptive requirements. The goals of RDF are broad, and the potential opportunities are enormous. This introduction to RDF begins by discussing the background context of the RDF initiative and relates it to other metadata activities. A discussion of the functionality of RDF and an overview of the model, schema and syntactic considerations of this framework follow. The history of metadata at the W3C began in 1995 with PICS, the Platform for Internet Content Selection [PICS]. PICS is a mechanism for communicating ratings of Web pages from a server to clients. These ratings, or rating labels, contain information about the content of Web pages; for example, whether a particular page contains a peer-reviewed research article or was authored by an accredited researcher or contains sex, nudity, violence, foul language, etc. Instead of being a fixed set of criteria, PICS introduced a general mechanism for creating rating systems. Different organizations could rate content based on their own objectives and values, and users ‒ for example, parents worried about their children's Web usage ‒ could set their browsers to filter out any Web pages not matching their own criteria. Development of PICS was motivated by the anticipation of restrictions on Internet content in the United States and elsewhere. Through a series of meetings with the digital library community, limitations in the PICS specifications were identified, and functional requirements were outlined to address the more general problem of associating descriptive information with Internet resources based on the PICS architecture. As a result of these discussions, the W3C formed a new working group, PICS-NG Next Generation to address the more general issues of resource description [PICSNG]. Shortly after the PICS-NG working group was chartered, it became clear that the infrastructure designed in the early document specifications [PICSMOD] was applicable in several additional applications. As a result, the W3C consolidated these applications as the W3C Resource Description Framework working group. RDF is the result of a number of metadata communities bringing together their needs to provide a robust and flexible architecture for supporting metadata on the Web. While the development of RDF as a general metadata framework, and as such, a simple knowledge representation mechanism for the Web, was heavily inspired by the PICS specification [PICSSPEC], no one individual or organization invented RDF. RDF is a collaborative design effort. Several W3C member companies are contributing intellectual resources. It is drawing upon the XML [XML] design as well as proposals submitted by Microsoft [XMLDATA] and Netscape [MCFXML]. Other metadata efforts, such as the Dublin Core [DC] and the Warwick Framework [WF] have also influenced the design of the RDF. RDF provides a model for describing resources. Resources have properties (attributes or characteristics). RDF defines a resource as any object that is uniquely identifiable by a Uniform Resource Identifier (URI) [URI1] [URI2]. The properties associated with resources are identified by property types, and property types have corresponding values. Property types express the relationships of values associated with resources. In RDF, values may be atomic in nature (text strings, numbers, etc.) or other resources, which in turn may have their own properties. A collection of these properties that refers to the same resource is called a description. At the core of RDF is a syntax-independent model for representing resources and their corresponding descriptions [SPEC]. Figure 1 illustrates a generic RDF description. Bulletin of the American Society for Information Science The application and use of the RDF data model can be illustrated by concrete examples. Consider the following statements: 1. "The author of Document 1 is John Smith." 2. "John Smith is the author of Document 1." To humans, these statements convey the same meaning (that is, John Smith is the author of a particular document). To a machine, however, these are completely different strings. Whereas humans are extremely adept at extracting meaning from differing syntactic constructs, machines remain grossly inept. Using a triadic model of resources, property types and corresponding values, RDF attempts to provide an unambiguous method of expressing semantics in a machine-readable encoding. RDF provides a mechanism for associating properties with resources. So, before anything about Document 1 can be said, the data model requires the declaration of a resource representing Document 1. Thus, the data model corresponding to the statement "the author of Document 1 is John Smith" has a single resource Document 1, a property type of author and a corresponding value of John Smith. To distinguish characteristics of the data model, the RDF Model and Syntax specification [SPEC] represents the relationships among resources, property types and values in a directed labeled graph. In this case, resources are identified as nodes, property types are defined as directed label arcs and string values are quoted. Given this representation, the data model corresponding to the statement is graphically expressed as shown here: Bulletin of the American Society for Information Science If additional descriptive information regarding the author were desired, e.g., the author's e-mail address and affiliation, an elaboration on the previous example would be required. In this case, descriptive information about John Smith is desired. As was discussed in the first example, before descriptive properties can be expressed about the person John Smith, there needs to be a unique identifiable resource representing him. Given the directed label graph notation in the previous example, the data model corresponding to this description is graphically represented as shown here: Bulletin of the American Society for Information Science In this case, "John Smith" the string is replaced by a uniquely identified resource denoted by Author_001 with the associated property types of name, e-mail and affiliation. The use of unique identifiers for resources allows for the unambiguous association of properties. This is an important point, as the person John Smith may be the value of several different property types. John Smith may be the author of Document 1, but also may be the value of a particular company describing the set of current employees. The unambiguous identification of resources provides for the reuse of explicit, descriptive information. In the previous example the unique identifiable resource for the author was created, but not for the author's name, e-mail or affiliation. The RDF model allows for the creation of resources at multiple levels. Concerning the representation of personal names, for example, the creation of a resource representing the author's name could have additionally been described using "firstname," "middlename" and "surname" property types. Clearly, this iterative descriptive process could continue down many levels. What, however, are the practical and logical limits of these iterations? There is no one right answer to this question. The answer is dependent on the domain requirements. These issues must be addressed and decided upon in the standard practice of individual resource description communities. In short, experience and knowledge of the domain dictate which distinctions should be captured and reflected in the data model. The RDF data model additionally provides for the description of other descriptions. For instance, often it is important to assess the credibility of a particular description (e.g., "The Library of Congress told us that John Smith is the author of Document 1"). In this case the description tells us something about the statement "John Smith is the author of Document 1," specifically, that the Library of Congress asserts this to be true. Similar constructs are additionally useful for the description of collections of resources. For instance, "John Smith is the author of Documents 1, 2 and 3." While these statements are significantly more complex, the same data model is applicable. A more detailed discussion of these issues is outside the scope of this overview, but more information is available in the RDF Model and Syntax Specification [SPEC]. RDF defines a simple, yet powerful model for describing resources. A syntax representing this model is required to store instances of this model into machine-readable files and to communicate these instances among applications. XML is this syntax. RDF imposes formal structure on XML to support the consistent representation of semantics. RDF provides the ability for resource description communities to define semantics. It is important, however, to disambiguate these semantics among communities. The property type "author," for example, may have broader or narrower meaning depending on different community needs. As such, it is problematic if multiple communities use the same property type to mean very different things. To prevent this, RDF uniquely identifies property types by using the XML namespace mechanism [NS]. XML namespaces provide a method for unambiguously identifying the semantics and conventions governing the particular use of property types by uniquely identifying the governing authority of the vocabulary. For example, the property type "author" is defined by the Dublin Core Initiative as the "person or organization responsible for the creation of the intellectual content of the resource" and is specified by the Dublin Core CREATOR element [DCES]. An XML namespace is used to unambiguously identify the Schema for the Dublin Core vocabulary by pointing to the definitive Dublin Core resource that defines the corresponding semantics. Additional information on RDF Schemas is discussed latter. If the Dublin Core RDF Schema, however, is abbreviated as "DC," the data model representation for this example would be as follows: Bulletin of the American Society for Information Science This more explicit declaration identifies a resource Document 1 with the semantics of property type Creator unambiguously defined in the context of DC (the Dublin Core vocabulary). The value of this property type is John Smith. The corresponding syntactic way of expressing this statement using XML namespaces to identify the use of the Dublin Core Schema is <?xml:namespace ns = "http://www.w3.org/RDF/RDF/" prefix ="RDF" ?> <?xml:namespace ns = "http://purl.oclc.org/DC/" prefix = "DC" ?> <RDF:RDF> <RDF:Description RDF:HREF = "http://uri-of-Document-1"> <DC:Creator>John Smith<DC:Creator> </RDF:Description> </RDF:RDF> In this case, both the RDF and Dublin Core schemas are declared and abbreviated as "RDF" and "DC" respectively. The RDF Schema is declared as a boot-strapping mechanism for the declaration of the necessary vocabulary needed for expressing the data model. The Dublin Core Schema is declared in order to utilize the vocabulary defined by this community. The URI associated with the namespace declaration references the corresponding schemas. The element <RDF:RDF> (which can be interpreted as the element RDF in the context of the RDF namespace) is a simple wrapper that marks the boundaries in an XML document where the content is explicitly intended to be mappable into an RDF data model instance [spec]. The element <RDF:Description> (the element Description in the context of the RDF namespace) is correspondingly used to denote or instantiate a resource with the corresponding URI http://uri-of-Document-1. And the element <DC:Creator> in the context of the <RDF:Description> represents a property type DC:Creator and a value of "John Smith." The syntactic representation is designed to reflect the corresponding data model. In the more advanced example, where additional descriptive information regarding the author is required, similar syntactic constructs are used. In this case, while it may still be desirable to use the Dublin Core CREATOR property type to represent the person responsible for the creation of the intellectual content, additional property types "name," "email" and "affiliation" are required. For this case, since the semantics for these elements are not defined in Dublin Core, an additional resource description standard may be utilized. It is feasible to assume the creation of an RDF schema with the semantics similar to the vCard [VC] specification designed to automate the exchange of personal information typically found on a traditional business card, could be introduced to describe the author of the document. The data model representation for this example with the corresponding business card schema defined as CARD would be as seen here: Bulletin of the American Society for Information Science This, in turn, could be syntactically represented as <?xml:namespace ns = "http://www.w3.org/RDF/RDF/" prefix = "RDF" ?> <?xml:namespace ns = "http://purl.oclc.org/DC/" prefix = "DC" ?> <?xml:namespace ns = "http://person.org/BusinessCard/" prefix = "CARD" ?> <RDF:RDF> <RDF:Description RDF:HREF = "http://uri-of-Document-1"> <DC:Creator RDF:HREF = "#Creator_001"/> </RDF:Description> <RDF:Description ID="Creator_001"> <CARD:Name>John Smith<CARD:Name> <CARD:Email>smith@home.net<CARD:Email> <CARD:Affiliation>Home, Inc.<CARD:Affiliation> </RDF:Description> </RDF:RDF> in which the RDF, Dublin Core and the "Business Card" schemas are declared and abbreviated as "RDF," "DC" and "CARD" respectively. In this case, the value associated with the property type DC:Creator is now a resource. While the reference to the resource is an internal identifier, an external URI, for example, to a controlled authority of names, could have been used as well. Additionally, in this example, the semantics of the Dublin Core CREATOR element have been refined by the semantics defined by the schema referenced by CARD. This construct is similar to the Warwick Framework [WF], a recognition of separate maintainable and interchangeable packages of descriptive information used in the description of resources. The structural constraints RDF imposes to support the consistent encoding and exchange of standardized metadata provides for the interchangeability of separate packages of metadata defined by different resource description communities. RDF Schemas are used to declare vocabularies, the sets of semantics property types defined by a particular community. RDF schemas define the valid properties in a given RDF description, as well as any characteristics or restrictions of the property type values themselves. The XML namespace mechanism serves to identify RDF Schemas. A human and machine-processable description of an RDF schema may be accessed by de-referencing the schema URI. If the schema is machine-processable, it may be possible for an application to learn some of the semantics of the property-types named in the schema. To understand a particular RDF schema is to understand the semantics of each of the properties in that description. RDF schemas are structured based on the RDF data model. Therefore, an application that has no understanding of a particular schema will still be able to parse the description into the property-type and corresponding values and will be able to transport the description intact (e.g., to a cache or to another application). The exact details of RDF schemas are currently being discussed in the W3C RDF Schema working group [SCHEMA]. It is anticipated, however, that the ability to formalize human-readable and machine-processable vocabularies will encourage the exchange, use and extension of metadata vocabularies among disparate information communities. RDF schemas are being designed to provide this type of formalization. The World Wide Web affords unprecedented access to distributed information. Metadata improves access to this information and RDF is a W3C proposed standard for defining the architecture necessary for supporting Web metadata. RDF is an application of XML that imposes needed structural constraints to provide unambiguous methods of expressing semantics for the consistent encoding, exchange and machine processing of metadata. RDF additionally, provides means for publishing both a human-readable and a machine-processable vocabularies designed to encourage the exchange, use and extension of metadata semantics among disparate information communities. The potential implications of widespread adoption of RDF metadata on the Web are captured by Ora Lassila, editor of the RDF Model and Syntax Specification [IRDF]: Once the Web has been sufficiently "populated" with rich metadata, what can we expect? First, searching on the Web will become easier as search engines have more information available, and thus searching can be more focused. Doors will also be opened for automated software agents to roam the Web, looking for information for us or transacting business on our behalf. The Web of today, the vast unstructured mass of information, may in the future be transformed into something more manageable ‒ and thus something far more useful. The effective use of metadata among applications requires common conventions about semantics, syntax and structure. The design of enabling infrastructures such as RDF to support these constructs provides the necessary foundations to support the management of information on the Web and, as Ora suggests, provides the ability for transforming the Web into a more useful and powerful information resource. The author is indebted to several persons for helping with this article. Specifically, the author would like to credit Erik Jul, Ora Lassila, Ralph LeVan, R.V. Guha, Bob Schloss, Ralph Swick and Stuart Weibel for their comments, criticism, insight and support. Eric Miller is a research scientist at Online Computer Library Center, Inc. (OCLC), Office of Research in Dublin, Ohio. He can be reached by e-mail at emiller@oclc.org This article was originally published in D-Lib Magazine http://www.dlib.org/dlib/may98/miller/05miller.html, in May 1998. It is reprinted by permission of the author.

Purpose This paper seeks to understand how users know when to stop searching for more information when the information space is so saturated that there is no certainty that the relevant information has been identified. Design/methodology/approach Faculty, undergraduate and graduate students participated in focus group interviews to investigate what leads them to satisfice their information needs. Findings Academic library users describe both qualitative and quantitative criteria, which lead them to make rational choices determining when “enough” information satisfices their need. The situational context of both the participants' specific information need and their role in academic society affects every stage of their search – from the selection of the first resource, to ongoing search strategies, to decisions on how much information is enough. Originality/value These findings broaden the scope of earlier user research, which tends to focus on the more static views of habitual information‐seeking and ‐searching behavior, by applying theoretical frameworks for a richer understanding of the users' experiences.

The term metadata simply means data about data. It is the term most often used in the Internet community for what has been known in the library community as cataloging data or resource description. The Dublin Core is a 15-element metadata element set intended to facilitate discovery of electronic resources. Originally conceived for author-generated description of Web resources, it has also attracted the attention of formal resource description communities such as museums and libraries. The Dublin Core Workshop Series has gathered experts from the library world, the networking and digital library research communities and a variety of content specialties in a series of focused, invitational workshops. The building of an interdisciplinary, international consensus around a core element set is the central feature of the three-year evolution of the Dublin Core. The progress represents the emergent wisdom and collective experience of many stakeholders in the resource description arena. An open mailing list supports ongoing work. The characteristics of the Dublin Core that distinguish it as a prominent candidate for description of electronic resources fall into several categories. The Dublin Core is intended to be used by non-catalogers. It is expected that authors or Web-site maintainers unschooled in the cataloging arts should be able to use the Dublin Core for resource description, making their collections more visible to search engines and retrieval systems. Most of the 15 elements have a commonly understood semantics that represents what might be described as a lowest common denominator for resource description (roughly equivalent to a catalog card). As such, the Dublin Core is not intended to replace richer description models such as AACR2/MARC cataloging, but rather to provide a core set of description elements that can be used by catalogers or non-catalogers for simple resource description. In the Internet commons, disparate description models interfere with the ability to search across discipline boundaries. For example, libraries, museums and the geographic information systems community use different standards for resource description. This reflects the different description needs of these communities and the fact that such standards have evolved independently. At a fine-grained description level, element sets are different because they must describe different things. Most writers seldom associate a cloud-cover attribute with their documents, but if you are describing satellite images of farmland, this is a critical descriptor. But most resources share a core set of attributes that are similar from one discipline to the next, but have different names simply because they have evolved independently and at different times. Promoting a commonly understood set of core descriptors will improve the prospects for cross-disciplinary search by unifying related attributes. For example, an author and a creator can be thought of as the same attribute for the purposes of resource discovery. The Dublin Core is intended to serve as this core element set. Recognition of the international scope of resource discovery on the Web is critical to the development of an effective discovery infrastructure. The Dublin Core has benefited from active participation and promotion in many countries around the world. Although initially motivated by the need for author-generated resource description, the Dublin Core has also attracted the attention of formal resource description communities. As the diversity and volume of Web resources increase, trusted intermediaries (such as museums and libraries) will achieve greater recognition as preferred sources of metadata for persistent resources. The Dublin Core, in the hands of cataloging experts, is expected to provide an economical alternative to more elaborate description models such as full MARC cataloging. The Dublin Core includes sufficient flexibility to encode the additional structure and more elaborate semantics appropriate to such applications. The wide diversity of metadata needs on the Web requires an environment that supports the coexistence of many independently developed and maintained metadata packages. The Dublin Core is targeted specifically toward resource discovery, but one can imagine many functionally distinct packages that serve other goals (terms and conditions, archival management, administrative metadata and many others). For example, a Terms and Conditions metadata package would include elements that describe rights holders, cost of acquiring a resource, restrictions on reuse of the resource and related information. Recognition of the desirability of this sort of modularity has guided the evolution of the Dublin Core since the Warwick Workshop and has been formalized as the Warwick Framework. The concepts articulated in this work have informed the ongoing development of a metadata architecture for the Web as well. The World Wide Web Consortium (W3C) is the primary standards forum for the Web and has recently begun to focus on implementing an architecture for metadata for the Web. The Resource Description Framework (RDF) is evolving to support the many different metadata needs of vendors and information providers. Representatives of the Dublin Core effort are actively involved in the development of this architecture, bringing the digital library perspective to bear on this important component of the Web infrastructure. The evolving RDF metadata architecture will support a variety of resource description models, each with implications for functionality and management. Embedded Metadata The easiest way of deploying metadata on the Web is by embedding it in HTML documents (using the META tag). Conventions exist to support inclusion of simple metadata in HTML versions 2.0 and above. The HTML 4.0 specification released in July includes additional attributes for the META tag that allow the qualifiers necessary for more complex implementations. The advantage of embedded metadata is that no additional system must be in place to use it; the metadata is integral to the resource and can be harvested by Web indexing agents. Third Party Metadata A model more familiar to the library community includes what is known in Web parlance as a third party label bureau, that is, an entity that collects and manages metadata records that refer to resources but are not embedded in the resource (a library catalog, for example). This model is important not only to libraries and museums, but also supports the development of agencies that might label resources according to age appropriateness or other acceptability criteria. View Filter A third model also involves management of records by a distinct entity, but not necessarily Dublin Core records per se. Managing a wide variety of data stores often involves reconciling very different description models. One approach to achieving interoperability in such an environment involves mapping many description schemas into a common set such as the Dublin Core, giving users a single query model. Much remains to be done to bring the Dublin Core to a state of sufficient maturity and stability to fulfill its promise as a foundation for resource discovery on the Net. The main thrusts of continued development include Continued Refinement of Dublin Core Elements The Dublin Core elements emerged from the collective judgment and experience of the many participants in the process to date. As deployment spreads, the evolution of the Dublin Core will reflect experience with the ambiguities, conflicts and deficiencies in the set. Standards of best practice will evolve in light of such experience. User Education and Application Guides The spread of a common set of resource description conventions depends in part on the availability of clear user guidelines. Such guidelines must be developed in many languages but with a common purpose and orientation. Metadata Registries The Warwick Framework describes the characteristics of an architecture for metadata that will allow independently developed metadata element sets to co-exist. This implies that the consumers of metadata (either people or software agents) will need formal, online registries that describe the semantics, the structure and the transport syntax of a metadata element set. Thus, an application finding Dublin Core metadata associated with a collection of resources might access the Dublin Core Metadata Registry to better understand the characteristics of the metadata. Work on metadata registries is still in an embryonic stage, but as the functional specifications evolve, they will become a central part of the infrastructure necessary to develop and manage change for a metadata set such as the Dublin Core. Tools Tools for creating and managing Web-based metadata are evolving now. As the infrastructure evolves and standards become stable, these tools will become commonplace in authoring, site management and resource management applications. Standardization The development of the Dublin Core has been a voluntary effort on the part of many disparate stakeholders in resource description. As it becomes more widely deployed, standards of best practice must be formalized. The Dublin Core Home Page: The official home page of the Dublin Core includes links to the workshop reports, the reference description of the element set and to projects using the Dublin Core, and the evolution of the Warwick Framework. http://purl.org/metadata/dublin_core The RDF Home Page: The home page of the RDF working group, maintained by the World Wide Web Consortium (W3C), reports developments of the metadata architecture on the Web. http://purl.org/w3c/rdf Crosswalks of Metadata Element Sets: Maintained by Michael Day at the United Kingdom Office for Library and Information Networking (UKOLN), this site is an excellent source for crosswalks and element mapping for a variety of metadata sets, including the Dublin Core. http://www.ukoln.ac.uk/metadata/interoperability The IFLA Metadata Home Page: A good collection of links to various metadata activities and related resources. http://www.nlc-bnc.ca/ifla/II/metadata.htm The UKOLN Metadata Page: A summary of publications, projects and metadata resources in general and projects in the UK in particular. http://www.ukoln.ac.uk/metadata The Dublin Core Elements See http://purl.org/metadata/dublin_core_elements for further information. TITLE The name given to the resource by the CREATOR or PUBLISHER. CREATOR The person(s) or organization(s) primarily responsible for creating the intellectual content of the resource. SUBJECT The topic of the resource: keywords or phrases that describe the subject or content of the resource, including controlled vocabularies or classification schemes. DESCRIPTIONS A textual description of the content of the resource, including abstracts in the case of document-like objects or content descriptions in the case of visual resources. PUBLISHER The entity responsible for making the resource available in its present form, such as a publisher, a university department or a corporate entity. CONTRIBUTOR Person(s) or organization(s) in addition to those specified in the CREATOR element who have made significant intellectual contributions to the resource but whose contribution is secondary to the individuals or entities specified in the CREATOR element (for example, editors, transcribers and illustrators). DATE The date the resource was made available in its present form. TYPE The category of the resource, such as home page, novel, poem, working paper, technical report, essay, dictionary. It is expected that TYPE will be chosen from an enumerated list of types. FORMAT The data representation of the resource, such as text/html, ASCII, Postscript file, executable application or JPEG image. IDENTIFIER String or number used to uniquely identify the resource. Examples for networked resources include URLs and URNs (when implemented). Other globally unique identifiers, such as International Standard Book Numbers (ISBN) or other formal names, would also be candidates for this element. SOURCE The work, either print or electronic, from which this resource is derived, if applicable. LANGUAGE Language(s) of the intellectual content of the resource. RELATION Relationship to other resources. The intent of specifying this element is to provide a means to express relationships among resources that have formal relationships to others, but exist as discrete resources themselves. COVERAGE The spatial and temporal characteristic of the resource. Formal specification of COVERAGE is currently under development. RIGHTS The content of this element is intended to be a link (a URL or other suitable URI as appropriate) to a copyright notice, a rights-management statement or perhaps a service that would provide such information dynamically.

The shortcomings and limitations of Library of Congress Subject Headings (LCSH) are examined, focusing on problems of subject term specificity, inconsistent identification and selection of concepts as subject headings, retention of outmoded headings, inadequate cross-reference structure, and low level of indexing exhaustivity. These problems are attributable to both Cutter's Rules for a Dictionary Catalog (the theoretical model upon which LCSH are based), and the unsystematic manner in which LC has applied Cutter's Rules in constructing entries for its subject catalog. Methods of improving subject access in libraries, for both on-line and printed catalog environments, are discussed.

OBJECTIVE: To document hepatozoonosis in dogs from Alabama and Georgia and to report associated clinical signs, method of diagnosis, response to treatment, and course of disease. DESIGN: Retrospective case series. ANIMALS: 22 dogs in which Hepatozoon canis was identified by microscopic examination of skeletal muscle. PROCEDURE: We reviewed medical records of all dogs with a definitive diagnosis of hepatozoonosis that were referred to the Auburn University Small Animal Clinic between 1989 and 1994. RESULTS: Diagnoses were confirmed by microscopic identification of H canis schizont or merozoite stages in skeletal muscle. The gametocyte stage was not detected in smears of blood obtained from a peripheral vein, buffy-coat smears, or bone marrow evaluation. Common clinical signs included fever, cachexia, ocular discharge, pain, stiffness, and paresis. Laboratory abnormalities included marked leukocytosis, hypoglycemia, hypoalbuminemia, mild anemia, hyperphosphatemia, and high alkaline phosphatase activity. Periosteal bone proliferation was evident radiographically in 18 of 22 dogs. Renal lesions included amyloidosis (1 dog), interstitial nephritis (3), and mesangioproliferative glomerulonephritis (4). Treatment with the anticoccidial drug toltrazuril, despite an initial favorable response, failed to prevent relapse in all but 3 of 21 treated dogs. Mean survival time was 12.6 +/- 2.2 months, with a mean time of remission before recurrence of clinical signs of 6 months. CLINICAL IMPLICATIONS: H canis infection in dogs can be associated with a distinct clinical syndrome that involves chronic myositis, debilitation, and death. The dogs of this report represent the first substantial number of domestic dogs naturally infected with H canis in the United States outside of the Texas Gulf Coast. Hepatozoon canis appears to be a serious pathogen in the United States that is becoming more widespread geographically.

Field archaeology only recently developed centralized systems for data curation, management, and reuse. Data documentation guidelines, standards, and ontologies have yet to see wide adoption in this discipline. Moreover, repository practices have focused on supporting data collection, deposit, discovery, and access more than data reuse. In this paper we examine the needs of archaeological data reusers, particularly the context they need to understand, verify, and trust data others collect during field studies. We then apply our findings to the existing work on standards development. We find that archaeologists place the most importance on data collection procedures, but the reputation and scholarly affiliation of the archaeologists who conducted the original field studies, the wording and structure of the documentation created during field work, and the repository where the data are housed also inform reuse. While guidelines, standards, and ontologies address some aspects of the context data reusers need, they provide less guidance on others, especially those related to research design. We argue repositories need to address these missing dimensions of context to better support data reuse in archaeology.

Much of the recent research on digital data repositories has focused on assessing either the trustworthiness of the repository or quantifying the frequency of data reuse. Satisfaction with the data reuse experience, however, has not been widely studied. Drawing from the information systems and information science literature, we developed a model to examine the relationship between data quality and data reusers' satisfaction. Based on a survey of 1,480 journal article authors who cited I nter‐ U niversity C onsortium for P olitical and S ocial R esearch ( ICPSR ) data in published papers from 2008–2012, we found several data quality attributes—completeness, accessibility, ease of operation, and credibility—had significant positive associations with data reusers' satisfaction. There was also a significant positive relationship between documentation quality and data reusers' satisfaction.

In Brief Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination is associated with lower odds of severe or critical coronavirus disease 2019 (COVID-19) or COVID-19 of any severity in pregnant patients during the Delta-predominant fourth SARS-CoV-2 surge.

The authors analyzed the holdings, circulations, and interlibrary loan (ILL) borrowing requests of the English-language monograph collection at the University of Colorado at Boulder. Data for each area were mapped to conspectus subject areas, using Library of Congress Classifications, and then compared. The resulting data and subject distributions were analyzed by overall holdings, transactions per item, percentage of collection circulated, and a ratio of ILL holdings to requests. The method of analysis used in this study could be fruitfully applied to other research collections to assist with remote storage, preservation, and collection development decisions.

OBJECTIVES: The aim of the study was to retrospectively evaluate the effectiveness of a fertility awareness-based method supported by a mobile-based application to prevent unwanted pregnancies as a method of natural birth control. METHODS: In a retrospective analysis, the application's efficiency as a contraceptive method was examined on data from 4054 women who used the application as contraception for a total of 2085 woman-years. RESULTS: The number of identified unplanned pregnancies was 143 during 2053 woman-years, giving a Pearl Index of 7.0 for typical use. Ten of the pregnancies were due to the application falsely attributing a safe day within the fertile window, producing a perfect-use Pearl Index of 0.5. Calculating the cumulative pregnancy probability by life-table analysis resulted in a pregnancy rate of 7.5% per year (95% confidence interval 5.9%, 9.1% per year). CONCLUSIONS: The application appears to improve the effectiveness of fertility awareness-based methods and can be used to prevent pregnancies if couples consistently protect themselves on fertile days.

A challenge facing libraries is to develop and update collections and services to meet the needs of the multiple generations of users with differing approaches to information seeking. The different characteristics and information needs of 'Baby Boomers' and 'Millennials' present a dichotomy for library service and system development. Results are reported here for two research projects that investigated habits and needs of library users and non-users. Both studies sought to identify how and why individuals seek and use information. The first study deals with the findings of focus group interviews with seventy-eight randomly selected participants, and fifteen semi-structured interviews with a subset of these participants. The second study reports the results of focus group interviews with twenty-three Millennials, and an analysis of 492 virtual reference services (VRS) transcripts. The studies indicate that both generations consistently identify Google and human sources as the first sources they use for quick searches. The younger Millennials mentioned consulting parents most frequently, while the older Millennials consult friends and professors. Baby Boomers indicate that they consult their personal libraries and colleagues. The findings have implications for the development of next generation library online catalogs, as well as services, including VRS.

Purpose Taking the researchers’ perspective, the purpose of this paper is to examine the types of context information needed to preserve data’s meaning in ways that support data reuse. Design/methodology/approach This paper is based on a qualitative study of 105 researchers from three disciplinary communities: quantitative social science, archaeology and zoology. The study focused on researchers’ most recent data reuse experience, particularly what they needed when deciding whether to reuse data. Findings Findings show that researchers mentioned 12 types of context information across three broad categories: data production information (data collection, specimen and artifact, data producer, data analysis, missing data, and research objectives); repository information (provenance, reputation and history, curation and digitization); and data reuse information (prior reuse, advice on reuse and terms of use). Originality/value This paper extends digital curation conversations to include the preservation of context as well as content to facilitate data reuse. When compared to prior research, findings show that there is some generalizability with respect to the types of context needed across different disciplines and data sharing and reuse environments. It also introduces several new context types. Relying on the perspective of researchers offers a more nuanced view that shows the importance of the different context types for each discipline and the ways disciplinary members thought about them. Both data producers and curators can benefit from knowing what to capture and manage during data collection and deposit into a repository.

The report from the IFLA Study Group on the Functional Requirements for Bibliographic Records (FRBR) recommended a new approach to cataloging based on an entity-relationship model. This study examined a single work, The Expedition of Humphry Clinker , to determine benefits and drawbacks associated with creating such an entity-relationship model. Humphry Clinker was selected for several reasons—it has been previously studied, it is widely held, and it is a work of mid-level complexity. In addition to analyzing the bibliographic records, many books were examined to ensure the accuracy of the resulting FRBR model. While it was possible to identify works and manifestations, identifying expressions was problematic. Reliable identification of expressions frequently necessitated the examination of the books themselves. Enhanced manifestation records where the roles of editors, illustrators, translators, and other contributors are explicitly identified may be a viable alternative to expressions. For Humphry Clinker , the enhanced record approach avoids the problem of identifying expressions while providing similar functionality. With the enhanced manifestation record, the three remaining entity-relationship structures—works, manifestations, and items—the FRBR model provides a powerful means to improve bibliographic organization and navigation.

The paper considers how the changing nature of research in digital environments is reshaping the nature of library collections and services in academic and research libraries. It describes two central directions, each a response to the centrality of the user in a network environment. First, the library has an increasing role in managing the research and other outputs of the university (the inside-out collection). Second, the library is facilitating access to a broader range of local, external and collaborative resources organized around user needs (the facilitated collection).

The global energy demand for digital activities is constantly growing. Computing nodes and cloud services are at the heart of these activities. Understanding their energy consumption is an important step towards reducing it. On one hand, physical power meters are very accurate in measuring energy but they are expensive, difficult to deploy on a large scale, and are not able to provide measurements at the service level. On the other hand, power models and vendor-specific internal interfaces are already available or can be implemented on existing systems. Plenty of tools, called software-based power meters, have been developed around the concepts of power models and internal interfaces, in order to report the power consumption at levels ranging from the whole computing node to applications and services. However, we have found that it can be difficult to choose the right tool for a specific need. In this work, we qualitatively and experimentally compare several software-based power meters able to deal with CPU or GPU-based infrastructures. For this purpose, we evaluate them against high-precision physical power meters while executing various intensive workloads. We extend this empirical study to highlight the strengths and limitations of each software-based power meter.

OBJECTIVE: To investigate the frequency of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies in parturient women, their partners, and their newborns and the association of such antibodies with obstetric and neonatal outcomes. METHODS: From April 4 to July 3, 2020, in a single university hospital in Denmark, all parturient women and their partners were invited to participate in the study, along with their newborns. Participating women and partners had a pharyngeal swab and a blood sample taken at admission; immediately after delivery, a blood sample was drawn from the umbilical cord. The swabs were analyzed for SARS-CoV-2 RNA by polymerase chain reaction, and the blood samples were analyzed for SARS-CoV-2 antibodies. Full medical history and obstetric and neonatal information were available. RESULTS: A total of 1,313 parturient women (72.5.% of all women admitted for delivery at the hospital in the study period), 1,188 partners, and 1,206 newborns participated in the study. The adjusted serologic prevalence was 2.6% in women and 3.5% in partners. Seventeen newborns had SARS-CoV-2 immunoglobulin G (IgG) antibodies, and none had immunoglobulin M antibodies. No associations between SARS-CoV-2 antibodies and obstetric or neonatal complications were found (eg, preterm birth, preeclampsia, cesarean delivery, Apgar score, low birth weight, umbilical arterial pH, need for continuous positive airway pressure, or neonatal admission), but statistical power to detect such differences was low. Full serologic data from 1,051 families showed an absolute risk of maternal infection of 39% if the partner had antibodies. CONCLUSION: We found no association between SARS-CoV-2 infection and obstetric or neonatal complications. Sixty-seven percent of newborns delivered by mothers with antibodies had SARS-CoV-2 IgG antibodies. A limitation of our study is that we lacked statistical power to detect small but potentially meaningful differences between those with and without evidence of infection.

The purpose of this study was to analyze trends in publication and citation in library and information science journals over a decade (1994–2004) of the literature. This examination revealed the areas of concentration within the research, frequently published subjects through the years, and the characteristics of the top-cited authors and resources during this time. This information allows those in the field to follow the trends in publication, gives researchers the tools to determine which journals might give their work the most exposure and recognition, and can help libraries to make collection management decisions in this subject area.

The American Industrial Hygiene Association (AIHA) and American Conference of Govermental Industrial Hygienists (ACGIH) Respiratory Protective Devices Manual, published in 1963, has as its primary source of physiological background the work of Silverman and co-workers performed during World War II. The adoption of permanent OSHA standards governing work tasks requiring workers to use respirators has created a need for further evaluation of the physiological effects of wearing a respirator. This review was undertaken to meet the need of an in-depth evaluation of the currently available psychophysiological data. It was concluded that it was of the utmost importance to develop a physiological and psychological medical screening examination to determine the capability of the worker to use a respirator.

This paper explores the concept of a work in WorldCat, the OCLC Online Union Catalog, using the hierarchy of bibliographic entities defined in the Functional Requirements for Bibliographic Records (FRBR) report. A methodology is described for constructing a sample of works by applying the FRBR model to randomly selected WorldCat records. This sample is used to estimate the number of works in WorldCat, and describe some of their key characteristics. Results suggest that the majority of benefits associated with applying FRBR to WorldCat could be obtained by concentrating on a relatively small number of complex works.

The paper describes a project to add value to controlled vocabularies by making inter-vocabulary associations. A methodology for mapping terms from one vocabulary to another is presented in the form of a case study applying the approach to the Educational Resources Information Center (ERIC) Thesaurus and the Library of Congress Subject Headings (LCSH). Our approach to mapping involves encoding vocabularies according to Machine-Readable Cataloging (MARC) standards, machine matching of vocabulary terms, and categorizing candidate mappings by likelihood of valid mapping. Mapping data is then stored as machine links. Vocabularies with associations to other schemes will be a key component of Web-based terminology services. The paper briefly describes how the Open Archives Initiative Protocol for Metadata Harvesting (OAI-PMH) is used to provide access to a vocabulary with mappings.