Anthony Isenor

Moving Between Standards (Crosswalking)

Crosswalks are human- or computer-readable documents that map metadata elements between different metadata standards.

Crosswalks can apply to content standards, vocabularies, or both. An automated crosswalk process may take an instance of a metadata description that is presented in a particular format and change the format and element names and the values within those elements (i.e., the vocabulary) to meet the requirements of the second standard.

Common Metadata Standards

This guide describes several standards that offer a good starting point for those seeking a generic metadata approach to their data: ISO 19115 and ISO 19139, CSDGM, DIF, Dublin Core, and ADN. This is not an exhaustive list, but it presents a selection of standards that have the following characteristics:

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:

Categories of Controlled Vocabularies

As defined in Classification of Controlled Vocabularies, vocabularies can be defined by their structure and form. There are three broad categories of controlled vocabularies: flat, multilevel, and relational (also called a relationship list). Within these three categories, there are a variety of types of controlled vocabularies. A type is a simplified name for vocabularies further classified by function. (Click on image to enlarge.)

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.

Harmonization of Metadata Standards

Metadata standards are often described in terms of element names and definitions. A standard defines the rules for how the metadata are structured and also the appropriate content for the various elements.

However, different standards can be stated in different ways. In other words, a particular standard (the source standard) doesn’t have to use the same element labels (names) for similar content, or allow the same terms to be filled in to each element as another standard (the target standard).

Getting Started - How You Can Publish Your Metadata

There is no one-size-fits-all approach to metadata. This guide is an overview of the steps in the metadata creation process from initial planning through publication in a metadata registry or repository. Even if your ultimate goal is not to publish your metadata, the initial steps below will still be relevant for planning your in-house metadata. 

Subscribe to RSS - Anthony Isenor