We have proprietary extensions to Microsoft Office Open XML already

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See Rob Weir’s blog entry “The Formats of Excel 2007.” Here’s an idea of how things are already reverting to the same old behavior, right when Microsoft is trying to convince the ISO how wonderful for interoperability their spec is supposed to be. Here’s a sample of what Rob says:

The “Excel Macro-Enabled Workbook” option saves as an “xlsxm” extension. It is OOXML plus proprietary Microsoft extensions. These extensions, in the form of binary blob called vbaProject.bin, represent the source code of the macros. This part of the format is not described in the OOXML specification.


This has some interesting consequences. It is effectively a container for source code that not only requires Office to run it, but requires Office to even read it. So you could have your intellectual property in the form of extensive macros that you have written, and if Microsoft one day decides that your copy of Office is not “genuine” you could effectively be locked out of your own source code.

For fun, they also threw in a brand new binary format (why, if the XML version is so great?):

The “Excel Binary Workbook” option caught me by surprise. This is not the legacy binary formats. This is not the new OOXML. This is a new binary format, with an “xlsb” extension. Similar to OOXML it has a Zip container file (the so-called Open Packaging Conventions container file format), but the payload consists (aside from a manifest) entirely binary files.

Stunning. Mind numbing.

Also See: An “OOXML is a bad idea” blog entry compendium


  1. Never forget the first rule of Microsoft as aptly demonstrated in this lightbulb joke:

    Q: How many Microsoft engineers does it take to change a lightbulb?
    A: Zero. Microsoft simply declares darkness to be the new standard.

  2. Okay, that’s a good joke Tim. However, even though I beta-tested Office ’07 with a dozen businesses throughout 2006, I had wondered about this macro code because even with the Office 2007 File Format Converter package, there is no mention of this in the documentation, and obviously, macros were not backward-compatible. I noticed the phenomenon, but not its implication.

  3. Unfortunately, most business are going to blindy upgrade to this new version. Most don’t even know about ODF yet, which is a shame. How are macros stored within ODF? Is this in the next version?

  4. I think the answer lies in the marketing question of ‘how do you get people to buy more of your profitable products’.

    Microsoft’s profitable products at the moment are Windows and Office, and the Microsoft answer to the question appears to be along the lines of ‘recruit unpaid volunteers into your distribution channel’ and ‘offer contracts to commercial customers that you cannot offer to consumers’.

    For the first, imagine that you have used Excel to create a spreadsheet which uses one of these ‘blobs’; then you email the spreadsheet to someone who needs to access it. Maybe it’s the business plan for the next quarter, and you need your bank manager to understand it to justify the loan you are taking. What can the bank manager do, apart from buy a copy of Excel ?

    For the second, if I want Office ‘retail’ as a consumer, I go into somewhere like Best Buy, put my cash down, and walk out with a box with some CDs in. On the back of the box in the small print it says ‘service end date 2017’, or something like that. And I have the right to expect that Microsoft will fix any serious defects until that date, but no longer; they fix defects in Windows roughly monthly.
    It seems to be different for ‘education’ customers, though; there is some prevarication in the UK
    which looks to be that schools have contracts which are more like leases; ‘pay for each computer you have, whether or not it is capable of running Office’, and ‘early termination charge if you want to discontinue’. You can’t get that deal in Best Buy, but a business is expected to understand the terms of any contract before it signs.

    IBM, of course, faces the same question; but is experienced enough to rephrase it as ‘what do you do when you can no longer get people to buy more of your profitable products’; and the answer is generally ‘sell them off to cheaper producers, and develop something new’.
    http://www.lenovo.com/ now operate the old IBM Personal Computer business.
    http://www.serenity-systems.com/ (I think) now operate the old IBM OS/2 business.
    I think IBM still offers Lotus SmartSuite, but it is no longer actively marketed. If you know someone who would like to operate that business, there’s a good chance IBM would like to hear from you.

    One day, Microsoft might learn.

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