Metadata Standards

A metadataData about data. Metadata provides a context for research findings, ideally in a machine-readable format. It enables discovery of data via an electronic interface, and correct use and attribution of findings. Related Guide standardA set of documented rules which define the creation of metadata by providing a combination of terminology (vocabularies), syntactical rules, format rules, and other requirements. Metadata standards are approved, published and governed by a formal body or organization with broad community-based representation (international or national). Related Guide is a model for metadata storage that is approved by a recognized standards organization, such as ISOInternational Standards Organization or FGDCFederal Geographic Data Committee . Metadata standards specify the kinds of information required to describe data. When a metadata document conforms to a standard, it is considered formal metadataMetadata that conforms to a specific standard, with consistent collection criteria, terminology and structure. Related Guide. Standards can provide very specific information about details such as valuesMetadata values are the content connected to metadata labels in a metadata element. For example, if the metadata label is "date", the metadata value could be "May 13, 2007". Related Guide to be provided and how to technically present the metadata.

Metadata standards can be of either or both of these two general types:

• Content standardsA list or hierarchy of required metadata elements to be included in the metadata description. Related Guide (also called descriptive standards)
• Format standardsA description of the digital storage and structural requirements of metadata which assures that different software programs are able to read or query the data. Related Guide (also called technical standards)

Content Standard 

A content standard specifies the information required to document a data set. It is a list or hierarchy of required metadata elementsIndividual instance of a metadata label and value pair. For example, "creator: John Doe" is a metadata element. Related Guide to be included in the metadata description, where the metadata element is considered the basic unit. Content standards include the name of each metadata element (also called the labelA descriptor for a metadata value. This can be thought of as a question to which the value is providing an answer. For example, for the metadata label "date", the metadata value could be "March 16, 2008".) and a definition for each name. For example, a common oceanographic metadata element is vessel. The definition would specify that this element should hold the name of the research vessel used to collect the data, and might further specify that the name be drawn from the ICES list of ship names. Each metadata element contains specific information, which when combined with content from other elements appropriately describe a data set.

The content standards also requires a set of statements that formally express the rules of usage for the collection of metadata elements. For example, a rule might specify that a particular element is mandatory, or that if one element is included (such as a parameter name) that another element must also be provided (such as the units for the parameter). approved model—the definition of metadata elements and their rules for use—when implemented by multiple projects, helps ensure common practices across existing projects and helps users develop a sound metadata plan for a new project.

Format Standard 

While content standards describe the information that should be captured, format standards express how that information should be represented. HTMLHyperText Markup Language , XMLeXtensible Markup Language , NetCDFNetwork Common Data Format , and delimited text are all common formats. Format standards are critical for allowing machine readabilityIn the context of metadata, formatted in a way that is well defined and processable by the system's software and hardware. Metadata with this characteristic can be discovered, ingested, and presented by an electronic system (also known as 'computable'). Related Guide of metadata. Some metadata standards, such as ISO 19139, are both format and content standards.

Use of Content and Format Standards 

The integration of the content standard and format standard concepts allows for consistency of information that is included in a metadata set, the structure that is used to store the metadata, and where the metadata are stored within this structure. By carefully articulating how the metadata elements are named, structured, and utilized, metadata standards enable interoperabilityThe ability of two or more information systems to exchange metadata with minimal loss of information. Related Guide and allow for the creation of tools to work with the metadata, such as searchable repositories and metadata creation templates. See more about this topic in The Importance of Metadata Standards.

Additional Reading 

For an interesting discussion of formal metadata, see the Metadata Challenges presentation by Dr. Sara Graves.