The old issue of Mac/PC incompatibility has reared its head once more: Mac users cannot open documents saved in the default format on Microsoft Office 2007 for Windows.

By default, Office 2007 saves documents in what the company calls 'Microsoft Office Open XML'. The new format applies across Word, Excel and PowerPoint applications on PCs using Office 2007. The formats are specifically termed docx, xlsx and pptx.

Office 2003 for Windows users can download a compatibility pack that makes it possible to open Office 2007 documents.

However, the company's Mac Business Unit hasn't yet delivered similar software for existing Mac installations of Office. It has promised to ship them, but hasn't yet committed to a specific date for this.

There is some hope – and a hint that Mac users may not have to wait too long to enjoy cross-platform parity with Windows: Novell has promised it will release code that supports the new Office 2007 formats to the open source developers of its alternative (and free) productivity suite, This support is scheduled to debut "by the end of January". Novell will also release translation software to help documents created in either suite to be opened in the other.

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