The Spreadsheet::WriteExcelXML module can be used to create an
Excel file in XML format. The Excel XML format is supported in
Excel 2002 and 2003.

Multiple worksheets can be added to a workbook and formatting
can be applied to cells. Text, numbers, and formulas can be
written to the cells. The module supports strings up to 32,767
characters and the strings can be in UTF8 format.

Spreadsheet::WriteExcelXML uses the same interface as
Spreadsheet::WriteExcel.

This module cannot, as yet, be used to write to an existing
Excel XML file.