Once the documentation of the .pst format is public, programmers can get into .pst files and read the contents without the need for Outlook. In fact, there will be no requirement for any Microsoft software. Users are free to choose any platform, including Linux and any development language, such as Java or Ruby on Rails.

Data in the .pst file is available to developers today via Microsoft's Messaging API (MAPI) and the Outlook Object Model, but Outlook needs to be installed on the desktop.

Microsoft Monday was entertaining a number of customers and partners on its Redmond campus to help gather feedback on the documentation. The technical documentation will detail how the data is stored, along with guidance for accessing that data from other software applications.

Critics such as the Software Freedom Law Center have warned that inconsistencies are possible between Microsoft formats available under OPS and with the open source GPL license.

Microsoft last year added language to OPS on patent/copyright coverage and information on how OSP interacts with GPL-based software development.