There are a number of common questions in relation to this standardisation effort that I've heard many times - these are my short answers to each:

1. Do other standardised document formats not exist today?
   Yes, in fact there are actually many different and at times overlapping formats that exist today, for instance PDF/A, ODF and HTML are all ISO/IEC standard document types today. 
   
2. Why do we need multiple standardised formats?
   Multiple formats are required as requirements change and to cater for differing scenarios for instance PNG and JPEG are two ISO/IEC image standards in heavy use today.  Individuals and organisations will also continue to innovate and standards must evolve to keep pace with this, for instance MPEG-1, MPEG-2 and MPEG -4 are all ISO/IEC standards for video encoding.
   
3. What is the impact to the industry if Open XML is not accepted as an ISO/IEC standard?
   Literally billions of documents today are stored and saved using Microsoft Office file formats, an important aspect of Open XML is backwards compatibility for these documents.  Not standardising Open XML will have an impact on the longevity of these documents and force government departments, individual organisations and consumers to migrate all of their documents over time.  It will also significantly reduce the choice available to our customers in relation to document formats.
   
4. What is the impact to Microsoft if Open XML is not accepted as a standard?
   While standards themselves don’t dictate customer and partner behaviour or purchasing patterns they do have a strong influence on this over time.  As a result there is likely to be a direct impact on the adoption of Microsoft products if Open XML is not accepted as a standard that will reduce our ability to compete in the marketplace.