Programming Excel with VBA and .NET

Understand XML

Simply put, XML is a way to store data as plain text. This is useful because it allows all sorts of hardware and software to exchange data and, more importantly, understand that data.

Excel 2003 supports XML at two levels:

• The XML spreadsheet file format lets you save and open Excel workbooks stored as plain text in XML format.

• Lists and XML maps let you import and export XML to a range of cells in a worksheet.

The concept behind XML has been around for a very long time. The core idea is that if you store content in plain text, add descriptive tags to that content, then describe those tags somewhere, you enable that content to be shared across applications, networks, and hardware devices in some very interesting ways.

XML is the standard for tagging content and navigating among those tags. XML has related standards for describing tags and transforming documents. All of these standards are maintained by W3C and are published at www.W3C.org. There are quite a few acronyms associated with XML, and the following tables will help you understand them. Table 15-1 lists the XML language standards .

Table 15-1. XML language standards

Acronym	Full name	Use to
XML	Extensible Markup Language	Describe data as plain text documents.
XPath	XML Path Language	Define parts of an XML document and navigate between those parts.
DTD	Document Type Definition	Define the tags used to identify content in an XML document.
XSD	XML Schema Definition	An XML-based version of ...