About XML
XML (Extensible Markup Language) is way to repurpose data in a file or automate the process of replacing the data in one file with data from another file. XML employs tags to describe parts of a file—a heading or a story, for example. These tags mark data so it can be stored in an XML file and handled appropriately when it is exported to other files. Think of XML as a translation mechanism for data. XML tags label text and other content in a file so that applications can recognize and present the data.
Extensible language
XML is considered an extensible language because individuals create their own XML tags—they can create one tag for each type of information that they want to repurpose. XML tags don’t carry information about how data is supposed to be displayed or formatted. XML tags are strictly for identifying content.
In InDesign, for example, you can create a Heading1 tag and assign it to each first-level heading in a document. After you save the document as an XML file, the Heading1 content can be imported and put to use—by any application that can read XML—as a web page, printed catalog, directory, price list, or database table.
InDesign is one of many applications that can produce and use XML. After you tag content in an InDesign file, you save and export the file as XML so that it can be repurposed in another InDesign file or another application. Similarly, you can import an XML file into InDesign and instruct InDesign to display and format the XML data any way you want.
In InDesign, you can create XML tags and tag parts of a document even if you’re not experienced with XML. InDesignhandles XML programming behind the scenes and creates the XML for you when you export a document in XML format.
XML data structure
The element is the building block of XML data; an element is data that has been tagged. In XML files, elements are nested within other elements to create a hierarchical structure for the data.
You can see the structure of XML data in the Structure pane, which displays the hierarchy and sequence of elements. In the XML structure, child elements are contained by parent elements, which in turn may also be child elements. Or, seen from the other direction, parent elements contain child elements, and these child elements may in turn be parent elements to other child elements.
For example, in the following image, you can see a chapter element that contains (is the parent of) several recipe elements. Each recipe element, in turn, is the parent of elements called recipename, ingredients, instructions, notes, and servings. All elements are contained inside the Root element, which always appears at the top of the Structure pane.
For more information on using XML in InDesign, visit www.adobe.com/go/learn_id_XMLscript.