Rob Pegoraro of the Washington Post has a new blog post about Microsoft’s announced intention to publish the specification of the Personal Storage Table (.pst) file format used by its Outlook E-mail and personal information management application.
By documenting the workings of Outlook’s Personal Storage Table (PST) format–one of my least-favorite locked formats–Microsoft would make it far easier for developers to write Outlook-compatible software to complement or replace that widely used program.
The announcement was made in a post yesterday on Microsoft’s “Interoperability@Microsoft” blog, by Mr. Paul Lorimer, Group Manager, Microsoft Office Interoperability, and also said that Microsoft would release the documentation under Microsoft’s Open Specification Promise:
When it [the documentation] is complete, it will be released under our Open Specification Promise, which will allow anyone to implement the .pst file format on any platform and in any tool, without concerns about patents, and without the need to contact Microsoft in any way.
Using proprietary file formats, and keeping the specification of those formats tightly under wraps, has historically been one of the key ways that Microsoft has made it difficult for users to switch to, or even add, non-Microsoft applications. So this announcement, following the publication last year of the binary format specifications for its Office products, is a significant, and welcome step toward a more open Windows environment.
Like Mr. Pegoraro, I have to say that I don’t have the Outlook file format (nor, in fact, Outlook itself) on my all-time favorites list. It uses a fixed-block allocation scheme that requires periodic compression operations to remove space occupied by “deleted” items, which otherwise are still there. (If you are old enough, you may remember doing an operation like this on indexed-sequential [ISAM] disk files under IBM’s OS/360.) Although the format presents a veneer of security, with password protection and selectable levels of “encryption”, the implementation of these features is lame in the extreme, and they are sufficient only to discourage the most unmotivated of snoops. And Outlook, in its early days, did a good deal to justify the way it was sometimes described then: “a virus-installation system that can also send and receive E-mail.”
Nonetheless, it is good to see that some of the repeated warnings about the risks of lock-in with closed formats seem to be having some effect. A data base (and that’s what an Outlook .pst file essentially is) is valuable because of the data it contains, not because it is stored in some clever (or not) format.