Appendix C: Addressing 2007 Office System Compatibility

The 2007 Office system has two primary compatibility risks at this time:

  • Office Web Components. OWC are no longer supplied with the 2007 Office system. OWC are a set of ActiveX controls that provide four key functionalities for OWC Web pages: Spreadsheet, Chart, PivotTable, and Data Source Control (DSC). Applications or existing Web pages that depend on OWC may no longer work. When installing the 2007 Office system, earlier versions of OWC will be removed from the computer. Microsoft does plan to make a version of OWC available for download.

  • Changes to the UI in the 2007 Office system. The 2007 Office system applications use the Ribbon as the primary UI. Custom applications that modified the appearance or functionality of the UI in earlier versions of Microsoft Office may no longer work correctly. These applications must be updated to support the new UI in the 2007 Office system.

New Default File Formats and Extensions

The 2007 Office system uses the new Office Open XML Formats, with corresponding four-letter file extensions. These new extensions replace the previous default file extensions. Table 16 lists the old file extensions with the corresponding replacements.

Table 16. The New File Extensions for the 2007 Office System

2007 Office system program

File type

Previous extension

2007 Office system default

2007 Office system macro-enabled







Workbook (XML)





Workbook (Binary)










Add-in module




Microsoft Office PowerPoint®











Add-in module
























The file extensions ending in “m” correspond to the macro-enabled versions of the new file format, where applicable. By default, macros are not enabled in 2007 Office system programs.

These new extensions and file formats may cause compatibility issues that will require changes to the application to function properly with the 2007 Office system, especially if the application saves or loads files. For more information about deploying the 2007 Office system, see the Office Deployment Guide.


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