Luis Bermudez

Vocabularies: Dictionaries, Ontologies, and More

Every discipline has its own terminology. Consider terms that are used to describe vertical distances. The word “altitude” refers to the distance of something above a reference point like ground level, such as an airplane in flight. If we were examining a set of blueprints for a building we would not use the word “altitude” to describe the level of the rooftop, even though it is also a vertical distance above ground level.

Classification of Controlled Vocabularies

In understanding English, if we want to figure out what a word means, we might consult a dictionary or a glossary. Or we may use an etymology dictionary to track the history of a word. If we want to know how a term relates to other terms we might consult a thesaurus.

Like the vocabulary sources for the English language, controlled vocabularies for describing metadata can be classified by their purpose, their form, or their functionalities.

Classification by Purpose

Vocabularies may be defined by their ability to accomplish specific goals:

Metadata Standards

A metadata standard is a model for metadata storage that is approved by a recognized standards organization, such as ISO or FGDC. Metadata standards specify the kinds of information required to describe data. When a metadata document conforms to a standard, it is considered formal metadata. Standards can provide very specific information about details such as values to be provided and how to technically present the metadata.

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

Metadata Extensions and Profiles

Customizing metadata standards with extensions and profiles

The Common Standards guide describes widely used standards for projects seeking a generic metadata approach. These standards were generally created for broad application, and thus usually represent the lowest common set of metadata that applies to many disciplines. These standards provide an organized way to represent many of the general characteristics of a dataset.

Writing Good Metadata

To create quality metadata, it is essential to include all the descriptive information necessary to locate, understand, and use a data set. You can save time and resources by leveraging the work and tools developed by others. Write your metadata in a standard fashion and adhere to the following rules and considerations (based on excerpts from the NOAA Coastal Services Metadata Workshop Materials).

Some Examples of Metadata

Metadata can apply to just about any data or information about your project; for instance, sensor configuration, data from the sensors, images, publications, or GIS layers. Therefore, it is helpful to have some examples to help plan what should go into your metadata records. The links below provide examples of metadata in several commonly used conventions from a variety of marine-related fields. Some pages provide links so the user may view the XML or text versions instead of the default HTML-rendered view.

Definition of Metadata

Metadata are used to describe data or information. In environmental sciences like oceanography, metadata describe the information that scientists collect and informs users about the characteristics and history of a data set or data item—including methodological, temporal and spatial information.

The word metadata is sometimes used in a singular form (metadata is). We use the plural (metadata are). Both are in common usage, though in the sciences it’s typically used in the plural.

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