Microsoft Office XML formats different from Office Open XML
The Microsoft Office XML formats are XML-based document formats (or XML schemas) introduced in versions of Microsoft Office prior to Office 2007. Microsoft Office XP introduced a new XML format for storing Excel spreadsheets and Office 2003 added an XML-based format for Word documents.
These formats were succeeded by Office Open XML (ECMA-376) in Microsoft Office 2007.File formats
Microsoft Office Word 2003 XML Format — WordProcessingML or WordML (.XML)
Microsoft Office Excel 2002 and Excel 2003 XML Format — SpreadsheetML (.XML)
Microsoft Office Visio 2003 XML Format — DataDiagramingML (.VDX, .VSX, .VTX)
Microsoft Office InfoPath 2003 XML Format — XML FormTemplate (.XSN) (Compressed XML templates in a Cabinet file)
Microsoft Office InfoPath 2003 XML Format — XMLS FormTemplate (.XSN) (Compressed XML templates in a Cabinet file)Limitations and differences with Office Open XML
Besides differences in the schema, there are several other differences between the earlier Office XML schema formats and Office Open XML.Whereas the data in Office Open XML documents is stored in multiple parts and compressed in a ZIP file conforming to the Open Packaging Conventions, Microsoft Office XML formats are stored as plain single monolithic XML files (making them quite large, compared to OOXML and the Microsoft Office legacy binary formats). Also, embedded items like pictures are stored as binary encoded blocks within the XML. In case of Office Open XML, the header, footer, comments of a document etc. are all stored separately.
XML Spreadsheet documents cannot store Visual Basic for Applications macros, auditing tracer arrows, chart and other graphic objects, custom views, drawing object layers, outlining, scenarios, shared workbook information and user-defined function categories. In contrast, the newer Office Open XML formats support full document fidelity.
Poor backward compatibility with the version of Word/Excel prior to the one in which they were introduced. For example, Word 2002 cannot open Word 2003 XML files unless a third-party converter add-in is installed. Microsoft has released a Word 2003 XML Viewer which allows WordProcessingML files saved by Word 2003 to be viewed as HTML from within Internet Explorer. For Office Open XML, Microsoft provides converters for Office 2003, Office XP and Office 2000.
Office Open XML formats are also defined for PowerPoint 2007, equation editing (Office MathML), vector drawing, charts and text art (DrawingML).