In what is currently one of the biggest formats dispute that ever has taken place in IT industry, two sides, in one Microsoft almost alone, in the other all the remaining industry, it will be decided which document format will store all the Mankind documentation from now to future.
For almost all the rest of the IT industry, the choice is clear: Use one only (open) standard to avoid confusion and promote real free competition and an innovation environment. But which one? The response is obvious: The already existing and official OpenDocument Format, ISO 26300, that lets the consumers to choice among the greatest number of office applications (currently are available more than 50 apps. well supporting it ).
From the Microsoft side the response is clear also: Let's have two incompatible ISO standards in a way that finally only Microsoft can correctly implement the winner one and in this way it will continue holding the current monopoly in the office applications market. And why Microsoft thinks that "Office OpenXML" (ECMA-OOXML), its proposed standard to ISO, will be the winner standard? So easy, it starts from a dominating or indeed monopolistic position in the market. They think that all the current users of the different versions of its MS-Office suite will naturally migrate to its new format simply updating (paying for) to the recent new version of its current office applications and creating the well known network effect: If anybody sends an OOXML document, who recives it will be forced to use also the same new MS-Office to read it correctly, and at the same time s/he will send more OOXML documents to others in a way, at the end, to force everybody to use the new Microsoft format and the application to which it is tied to. This is the well known "vendor lock-in" classical strategy. Nothing new in IT.
This position is clearly described on this (silly?) Microsoft position paper:
- "Users Get to Decide their Document Formats" 
Published: June 15, 2007 | Updated: June 15, 2007
But, why nobody, except Microsoft, will be able to fully and correctly interpret and implement OOXML (officially named ECMA-376 or at this ISO stage as “DIS 29500”)?
Just a few reasons:
1) It is fully covered by software patents and there is no any worldwide legal warranty that they can be infringed without severe penalty. Microsoft just released a tiny "promisse", and the ECMA call-it-standardization-process doesn't warranty the disclosing of _all_ the patents by the members of the standardization committee (in this case, basically Microsoft itself). So, in any moment, we could find a new "235 patent menace" to any or all the "non-approved-by-Microsoft" ECMA-OOXML implementators. Go to history: Microsoft already is threatening in this way today to all Linux distributions.
2) Today nobody implements the proposed standard ECMA-OOXML. Neither Microsoft itself, who implements the sightly but enough different, original and undisclosed MS-OOXML.
3) The ECMA-OOXML specification containing more than 6.000 pages (perhaps should opt for the Guinnes Record) not even is complete. There are a lot of parts of the specification that refer to information that is not public, but Microsoft internal, eg. rules as "autoSpaceLikeWord95" or "useWord97LineBreakRules".
4) The ECMA-OOXML specification is not XML compliant and is tightly coupled to MS-Windows and MS-Office products, preventing in this way any 100% compatible implementation in competing platforms. There are parts of the specification that codify the information in binary format as printer formats (Windows dependant), Windows Metafiles, old binary VML with (just) 600 pages of specification instead of the (textually) "newer and richer" DrawingML proposed by Microsoft itself, "Custom Property Part" that not only is binary but also undefined in the specification, etc. Additionally, more than 10% of the examples mentioned in the specification does not validate XML conformity.
5) The ECMA-OOXML specification contradicts a lot of existing ISO standards such as ISO 8601 (Representation of dates and times), ISO 639 (Codes for the Representation of Names and Languages) or ISO/IEC 10118-3 (cryptographic hash algorithms). But also other open standards widely used as SVG, XForms, XSL-FO, MathML, etc. that on the contrary ISO 26300 respects.
6) The ECMA-OOXML specification includes indeed severe bugs as the one that prevents the representation of any date previous to the year 1900. The reason: It is a legacy bug heritaged from ancient 16bits MS-Office applications that has been implemented as is, instead of corrected, by all the MS-Office versions up to date.
7) Even standards have standards to follow. But ECMA-OOXML does not! ISO clearly states in its ISO/IEC Guide 2:2004, definition 3.2: "Standards should be based on the consolidated results of science, technology and experience, and aimed at the promotion of optimum community benefits." But on the contrary, no other player than Microsoft has been able to provide its "consolidated results", and so, it is intended only for Microsoft benefit.
So, as conclusion, OOXML is just a proprietary specification which is being pushed through the standardization acceptance process to protect Microsoft's interests and preserve the dominant market share that Microsoft Office currently holds.
Please, spread this information and vote against it! 
FFII Vice President
Open Standards coordinator
OpenXML (OOXML) no debe ser ISO 29500 (ES & PT)
 OpenDocument Fellowship: Applications supporting ODF:
 Microsoft: "Users Get to Decide their Document Formats"
 FFII: Petition "Say NO to the Microsoft Office format as an ISO standard"