The acronym XML stands for eXtensible Markup Language. You might be familiar with other markup languages, such as HTML (HyperText Markup Language). HTML uses tags to specify how a document — or in most cases, a Web page — is displayed. You use tags such as <p> for "start a new paragraph" and <b> for "put this text in boldface."

XML is not a true markup language; it's a language that lets you define tags for a markup language. Usually these tags refer to the content of the information, rather than its appearance. For example, a MetaSync XML file uses the tag <name> to mark the name of the enhancement and <locator> to mark its file location. When you import the XML file into another application, the application can read the XML file and find the name and location of the enhancement.

XML tags are defined in a special file called a document type definition, or DTD. MetaSync uses DTD files to define tags and to share information with other applications. For example, MetaSync DTD files define the tag <name> as META Name, the name of the enhancement as it is listed in MetaSync Manager. When an application sees information marked by the tag <name>, it uses that information to name the enhancement. Similarly, the DTD file defines the tag <locator> as File Location.

All MetaSync components use DTD files to make sure XML files match Avid specifications. For a table describing MetaSync DTD files, see Main Topics: MetaSync DTD Files (Windows Only).