Development Funding for PBCore provided by the
Corporation for Public Broadcasting

PBCore is a Metadata & Cataloging Resource
for Public Broadcasters & Associated Communities

About PBCore

The PBCore (Public Broadcasting Metadata Dictionary) was created by the public broadcasting community in the United States of America for use by public broadcasters and related communities. Initial development funding for PBCore was provided by the Corporation for Public Broadcasting.  The PBCore is built on the foundation of the Dublin Core (ISO 15836), an international standard for resource discovery (http://dublincore.org), and has been reviewed by the Dublin Core Metadata Initiative Usage Board.

 

Intrinsic to digital technology is the ability for each piece of content to carry with it some data describing that content in a useful way. This descriptive data is called metadata. To address the need to manage metadata within public broadcasting’s diverse community, version 1.1 of PBCore (the Public Broadcasting Metadata Dictionary) has been developed by a cross-organizational team of public radio and television producers and managers, archivists and information scientists.

PBCore is designed to provide—for television, radio and Web activities—a standard way of describing and using this data, allowing content to be more easily retrieved and shared among colleagues, software systems, institutions, community and production partners, private citizens, and educators. It can also be used as a guide for the onset of an archival or asset management process at an individual station or institution. Such a standard is pivotal to applying the real power of digital technology to meet the mission of public broadcasting.

We can now control every aspect of production and distribution to a degree never possible with analog technology. A common metadata protocol will make it easier to use content in new ways, on new platforms, by new constituents. PBCore will facilitate new production collaborations and the ability to parse traditional programs into short segments for Web distribution or as niche content for specific community, service and institutional needs. For these and other applications where granular manipulation and interoperability of content are required, PBCore will be essential.

The need for a shared descriptive language for public broadcasters was underscored in the results of the test implementations, as well as the March 2004 Request for Comments. Test participants affirmed the belief that their organizations and public broadcasting need PBCore to be widely available and in use by a majority of broadcasters. Ninety-six percent of the RFC respondents agreed "public broadcasting needs a core metadata dictionary," and that PBCore meets this need.

In addition, 44 percent of participants plan to implement a metadata project within a year, and 74 percent within two years. Respondents indicated the use of PBCore would provide public broadcasting with a necessary tool for increasing station and network efficiencies and inter-station resource sharing. And 80 percent agreed the use of PBCore could afford new service opportunities for their organization or those with whom they work.

Available free of charge to public broadcasting stations, distributors, vendors, and partners, version 1.0 of PBCore was launched in the first quarter of 2005 and version 1.1 was published in the first quarter of 2007. Please reference the links to Who May Use PBCore and PBCore Licensing for additional information about usage and implementation.

Funded by the Corporation for Public Broadcasting and administered by WGBH/Boston, a well-formed metadata dictionary directly addresses public broadcasting’s mission by making its award-winning content more easily accessible to teachers, scholars, lifelong learners, engaged citizens, and community partners.

Based on Dublin Core: The PBCore is built on the foundation of the Dublin Core (ISO 15836), an international standard for resource discovery (http://dublincore.org), and has been reviewed by the Dublin Core Metadata Initiative Usage Board.

Building a Community of Practice... A metadata dictionary and the situations in which it is applied are not static. Much work has been accomplished in order to define a core set of metadata descriptors for use by Public Broadcasters and their associated communities and partners. However, we are part of an evolutionary process that is building a "Community of Practice" for the uses and applications of the PBCore.

At the present time, the National Center for Accessible Media (NCAM), the WGBH Educational Foundation, is chartered as the official PBCore Authority and Maintenance Organization. This Authority will maintain the PBCore, in addition to providing user support, training, and PBCore metadata tools (see User Guide).

Contacts: As part of the PBCore Authority, a Project Director, is coordinating efforts to promote PBCore and assist in its application for your many data creation, manipulation and transport needs. At all times, we welcome feedback, questions, comments, concerns, requests, needs, and quandries about the PBCore. For specific contact information, link to our page Contacts.

Navigating the PBCore Website

The website is divided into sections accessible by clicking the buttons aligned vertically along the left hand margin of most pages. These buttons are repeated below along with text-based versions of the links.

	For further reading about the Project's Background and Participants
	To review each of the PBCore Metadata Elements
	To reference various sections of the PBCore User Guide or obtain the XML Schema Definition (XSD) representation of PBCore
	For confirmation on Who May Use the PBCore Metadata Elements
	For clarification on Licensing and Compliance Guidelines when using the PBCore Metadata Elements
	For informative Papers & Presentation, as well as Related Resources & Links
	For information on who to Contact regarding the Project and PBCore
	To access a Site Map outline of the CPB Metadata Website
	To access the PBCore XML Schema Definition (XSD) for the metadata schema
	To access the Mappings of PBCore to other metadata schemas
	To access the PBCore Namespace for the metadata schema
	To provide Feedback or submit questions and comments about PBCore
	To join the PBCore Listserv for announcements about PBCore events, features, and updates
	To identify training resources for PBCore and register for online WebEx sessions

 

The PBCore Metadata Elements

The Core?

The Public Broadcasting Metadata Dictionary (PBCore) is:

• a core set of terms and descriptors (elements)...
• used to create information (metadata)...
• that categorizes or describes...
• media items (sometimes called assets or resources).

The PBMD Project spent over two years comparing and contrasting various metadata descriptors, dictionaries, and schemes in order to arrive at the smallest set of descriptors or elements that could adequately describe and catalog the media items produced by Public Broadcasting radio and television stations that may be shared between stations, regional and national distributors, independent producers, and even vendors of Digital Asset Management systems.

The PBCore is a "core" because it can actually be considered a foundation of descriptors used to categorize media items adequately enough so other interested parties can successfully search for and review desired media items. The objective is to be able to share media items and give users complete, well-though-out, descriptions. Good descriptions help end users know what to expect when they decide to review, play or download a media file.

The PBCore is actually a starter kit and one that satisfies most users. However, as the PBCore is implemented by various communities, we will undoubtedly add optional extensions to the existing set of metadata elements to accommodate specials needs (see Extensions to the PBCore). Metadata descriptors related to the utilization of media items in educational settings is a good example of a relevant set of extensions to the PBCore.

 

 

---

How Many Elements?

Currently we have 53 elements arranged in 15 containers and 3 sub-containers, all organized under 4 content classes.

A more complete explanation is provided in the PBCore User Guide and the web page entitled Hierarchical Relationships and Interdependencies between Metadata Elements.

The hierarchy of roots, branches, and leaves is alternatively expressed in a data model as "Content Classes,' "Containers," "Sub-Containers," and "Elements."

CONTENT CLASSES
In the hierarchy of objects in the PBCore Description Document/Master Container, Content Classes are created as "conceptual wrappers" that cluster together a list or structure of thematically-related Elements (metadata fields and their attributes and properties). PBCore maintains four Content Classes as the conceptual wrappers for its various metadata elements:

1. PBCoreIntellectualContent
   9 containers; 16 elements
   (metadata elements describing the actual intellectual content of a media asset or resource)
2. PBCoreIntellectualProperty
   4 containers; 7 elements
   (metadata elements related to the creation, creators, usage, permissions, constraints, and use obligations associated with a media asset or resource)
   
3. PBCoreInstantiation
   1 container; 3 sub-containers; 28 elements
   (metadata elements that identify the nature of the media asset as it exists in some form or format in the physical world or digitally)
   
4. PBCoreExtensions
   1 container; 2 elements
   (additional descriptions that have been crafted by organizations outside of the PBCore Project. These extensions fulfill the metadata requirements for these outside groups as they identify and describe their own types of media with specialized, custom terminologies unique to their needs and community requirements)
   

ELEMENT CONTAINERS & SUB-CONTAINERS (aka "branches"):
Elements are objects in the PBCore schema hierarchy that define a metadata field and its values, attributes and properties. An element may be standalone. If several metadata fields are thematically related to each other, they can be bound together under an Element Container. Related elements are subsumed by a larger theme, and should be bound together when data is shared (particularly if an Element Container is a repeatable description with multiple instances of its related Elements). Examples of related Elements bound within a Container are *title* and its associated *titleType*, that are bound together by the Element Container *PBCoreTitle*. Within hierarchical structures, a Container may house Sub-Containers, which themselves bind together related Elements. In PBCore, there are Sub-Containers found within the Content Class PBCoreInstantiation.

ELEMENTS (aka "leaves"):
Elements are objects that define a metadata field and its values, semantics, attributes, and properties (for a list of the attributes defined for PBCore elements, see our web page PBCore Element Attributes). An Element is the actual "thing" that carries the descriptive metadata about a media item, such as a title, a date, keywords, rights information, mime types, media types, etc. The metadata elements are what a cataloger interacts with (creating descriptions) within a cataloging tool or asset management system.

To review detailed information and gain an understanding about the PBCore Elements, their use, case studies, and the PBCore XML Schema, use this link:

We have crafted a User Guide with multiple sections of information. Using the button...

...will take you to a menu of options for obtaining information about the PBCore elements, understanding what they mean, how to use them, as well as background information on the Project and related resources and links.

The PBCore is in Version 1.1

Since the initial publication (April 2005) of the Public Broadcasting Metadata Dictionary (PBCore v1.0), many stations, organizations and information systems began to use its 48 elements to describe the intellectual content, property rights, and instantiations/formats of their media items.

During this period, the PBCore project has been finalizing its XML Schema Definition (XSD) (for a discussion of XSD see The PBCore XML Schema web page). This XSD is the main framework upon which all the PBCore elements, their relationships, vocabulary picklists, and data types are organized and defined. The purpose of building an accurate and meticulous XSD is to ensure that when PBCore compliant metadata descriptions are shared between data systems, the contributing system and the receiving system are both able to "machine read" and faultlessly interpret and display the descriptions.

In the process of creating the PBCore XSD, we determined that some enhancements to the underlying structure of PBCore were necessary. For the most part, these enhancements are related to binding together related metadata elements (such as Title and TitleType) into new element containers. In a hierarchical arrangement, each element container collects and houses associated "child" elements that are thematically related. Basically, what was a "flat" arrangement of the 48 PBCore elements is becoming a more structured "hierarchical" model of 53 elements arranged in 15 containers and 3 sub-containers, all organized under 4 content classes. A more complete explanation is provided in the PBCore User Guide and the web page entitled Hierarchical Relationships and Interdependencies between Metadata Elements.

The underlying meaning and attributes of the PBCore elements are not changing. However, their inter-dependencies and structural arrangements are, along with some modifications to data entry options (see PBCore v1.1 Changes for more information). We feel the impending improvements to PBCore will greatly enhance its usability by Public Broadcasting communities and certainly improve the precision involved in sharing metadata between various information systems.