The EU's European Commission decided in March 2004 and reaffirmed last month objections to the software maker's market dominance, Microsoft said late Wednesday.
The company was fined about $600 million in 2004 and ordered to share details of its operating system with rival software makers.
"Today we are putting our most valuable intellectual property on the table so we can put technical compliance issues to rest and move forward with a serious discussion about the substance of this case," said Brad Smith, a top Microsoft executive.
"The Windows source code is the ultimate documentation of Windows Server technologies. With this step our goal is to resolve all questions about the sufficiency of our technical documentation."
Failure to comply with the commission could have exposed Microsoft to fines of up to about $2.5 million per day.
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