Before we delve into the mechanism, behind this technique a bit of
background on the new file format is in order.
Inside the Excel 2007 XML File Format
Excel 2007 builds on its history of XML support with a new file format called the Office Open
XML format. This new format improves file and data management, data recovery, and interoperability.
Any application that supports XML can access and work with information in an Excel
2007 workbook. This means it is now possible to work with your Excel data in systems outside
of Microsoft Office products as long as they provide XML support.
CHAPTER 3 n USING XML IN EXCEL 2007 119
Additionally, security concerns are reduced, since you now have your Excel data in what
is essentially a text file. This allows data to pass through firewalls without difficulty.
The new XML file format is based on the compressed ZIP file format specification. Each
ZIP container is made up of numerous XML files containing what Microsoft refers to as
???parts.??? While most parts are XML files describing workbook data, metadata, and document
information, non-XML files like binary files representing images or OLE objects may also be
included in the ZIP file. There are also relationship parts that describe the relationships
between parts, thus providing the structure for the workbook file. The parts are the content
of the workbook and the relationships detail how the content parts fit together.
Figure 3-20 shows the Open XML format??™s file container.
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