Metadata

Metadata is "data that provides information about other data". Two types of metadata exist: structural metadata and descriptive metadata. Structural metadata is data about the containers of data. Descriptive metadata uses individual instances of application data or the data content.

Metadata was traditionally in the card catalogs of libraries. As information has become increasingly digital, metadata is also used to describe digital data using metadata standards specific to a particular discipline. Describing the contents and context of data or data files increases their usefulness. For example, a web page may include metadata specifying what language the page is written in, what tools were used to create it, and where to find more information about the subject; this metadata can automatically improve the reader's experience.

The main purpose of metadata is to facilitate in the discovery of relevant information, more often classified as resource discovery. Metadata also helps organize electronic resources, provide digital identification, and helps support archiving and preservation of the resource. Metadata assists in resource discovery by "allowing resources to be found by relevant criteria, identifying resources, bringing similar resources together, distinguishing dissimilar resources, and giving location information."

The Metadata Company

Metadata is the name of a US corporation and a registered trademark in the United States.

Though the term "metadata" has a common generic use in information technology, claims of trademark have since brought about legal threats against its use in the generic sense.

History

The word Metadata was registered in 1986 as a trademark (U.S. Trademark Registration No. 1,409,206) belonging to The Metadata Company.. It was acknowledged that the term was first used in 1981 and the first commercial use tracked to 1982. The trademark was granted incontestable status in 1991. Metadata is a proprietary mark which stands for The Metadata Company.

The Metadata Company has since attempted to threaten people legally into not using the word "metadata" in the generic sense. Many people believe that due to the widespread use of the word "metadata" in the generic sense as "data about data", it is likely that the "Metadata" trademark has entered the public domain by becoming a general term. This was the legal opinion expressed by the Office of the Solicitor of the United States Department of the Interior to the Federal Geographic Data Committee when the latter was threatened by Metadata's lawyers for its use of the word "metadata" in a generic sense. However, no judge has as yet ruled the trademark invalid.

Metadata (CLI)

Metadata, in the Common Language Infrastructure (CLI), refers to certain data structures embedded within the Common Intermediate Language (CIL) code that describes the high-level structure of the code. Metadata describes all classes and class members that are defined in the assembly, and the classes and class members that the current assembly will call from another assembly. The metadata for a method contains the complete description of the method, including the class (and the assembly that contains the class), the return type and all of the method parameters.

A CLI language compiler will generate the metadata and store this in the assembly containing the CIL. When the run-time executes CIL it will check to make sure that the metadata of the called method is the same as the metadata that is stored in the calling method. This ensures that a method can only be called with exactly the right number of parameters and exactly the right parameter types.

The Windows Runtime application platform, present in Windows 8 and Windows Phone 8, makes use of the CLI metadata format to describe component interfaces for code written in any of the supported programming languages. A difference in use within the Common Language Runtime is that an assembly typically does not contain any CIL instructions.