XMP Specification September 2005 11 1 Introduction What is Metadata? Metadata is data that describes the characteristics or properties of a document. It can be distinguished from the main contents of a document. For example, for a word processing document, the contents include the actual text data and formatting information, while the metadata might include such properties as author, modification date, or copyright status. There can be gray areas where the same information could be treated as content or metadata, depending on the workflow. In general, metadata should have value on its own without regard for the content. For example, a list of all fonts used in a document could be useful metadata, while information about the specific font used for a specific paragraph on a page would be logically treated as content. Metadata allows users and applications to work more effectively with documents. Applications can do many useful things with metadata in files, even if they are not able to understand the native file format of the document. Metadata can greatly increase the utility of managed assets in collaborative production workflows. For example, an image file might contain metadata such as its working title, description, thumbnail image, and intellectual property rights data. Accessing the metadata makes it easier to perform such tasks as associating images with file names, locating image captions, or determining copyright clearance to use an image. File systems have typically provided metadata such as file modification dates and sizes. Other metadata can be provided by other applications, or by users. Metadata might or might not be stored as part of the file it is associated with. What is XMP? In order for multiple applications to be able to work effectively with metadata, there must be a common standard that they understand. XMP—the Extensible Metadata Platform—is designed to provide such a standard. XMP standardizes the definition, creation, and processing of metadata by providing the following: ● A data model: A useful and flexible way of describing metadata in documents: see Chapter 2, “XMP Data Model”. ● A storage model: The implementation of the data model: see Chapter 3, “XMP Storage Model”. This includes the serialization of the metadata as a stream of XML and XMP Packets, a means of packaging the data in files. Chapter 5, “Embedding XMP Metadata in Application Files”, describes how XMP Packets are embedded in various file formats.