Many a Linux user has already stumbled upon .pst documents, such as attached to emails in "Outlook Format." Microsoft now wants to publish documentation for the file format.

Under the keyword "interoperability," Microsoft group manager Paul Lorimer indicated in his blog that the company will make its Outlook Personal Folders format (.pst) specification available to more than just its developers. The publication should make it easier for anyone to write a program or library to handle the file format without needing written permission from Microsoft.

However, releasing the documentation is not under a free license, but under the Microsoft Open Specification Promise, an intellectual property rights implementation initiated in 2006 whereby Microsoft promises not to file claims against use of certain of their licensed or patented technologies. A similar Community Promise from 2007 applied to the free Mono .NET implementation.

According to Lorimer's blog, the PST specification is still in an early draft, with an exact release date still TBD.