Metadata must be standardized to be effective for discovery, usage, sharing, and management. Standardization involves creating consistent and structured metadata according to established rules or guidelines (e.g., for formatting, naming, spelling, language). Without metadata standards, it can be difficult to correctly interpret data and to compare, link, or integrate across datasets. 

The terms metadata standard, metadata schema, and application profile are often used interchangeably, but they each serve a different purpose.   

• A metadata standard is a high-level document that establishes a common way of structuring and understanding metadata and includes requirements for utilizing the standard. It defines the structure or format (syntax) and meaning (semantics) of metadata elements (sometimes called “metadata fields”). It might also include recommendations for controlled vocabularies or encoding practices. 

• A metadata schema is a logical plan that provides the exact structure for how metadata should be organized, including definitions of the elements, attributes, data types, and the relationships between different elements. A metadata schema is often published in an encoded form, such as XSD (XML Schema Definition), which can be used for validation.

• An application profile describes the use of metadata elements declared in a metadata standard and/or schema for a specific application or use case. It specifies rules and guidelines for the use of the elements, identifies element obligations and constraints (e.g., controlled vocabularies, name authorities, and encoding schemes), and provides comments and examples to assist in the understanding of the elements. An application profile may include metadata elements integrated from one or more metadata standards/schema.  

In a sense, the metadata standard establishes the rules, the metadata schema enforces them, and the application profile defines and documents any variables in a specific implementation. 

The Library’s Metadata and Discovery Unit provides metadata advice and support.  To ask a question, set up a consultation, or learn more about our services, contact us.