SEATTLE – Microsoft Corp. is seeking to standardize the document format used for its popular Office products, partly in response to concerns that documents stored using its proprietary technology may be difficult to access in years to come.

The company’s proposal to Ecma International, a Geneva-based industry group that develops and publishes technical standards, would make Microsoft Office Open XML an international standard.

Alan Yates, general manager of information worker strategy at Microsoft, said the company would then provide a simple, free license to anyone who wants it, making it easy for others – including possibly rival companies – to build products and other ways to access the information.

The move comes as companies and governments are growing more concerned that electronic information will be hard to access if intellectual property concerns, compatibility problems or other issues come up years from now.

A document stored today, for instance, might not be readable at all 10 or 15 years from now if Microsoft decides to change its formats and computers no longer exist to run today’s versions of Microsoft products. Publishing the standards leaves open the possibility that someone else would develop programs then to run today’s formats.

“It gives them the confidence that there is a foundation for documents that is not controlled by just one company but is a real consensus within the industry,” Yates said.

It’s a similar strategy taken by Adobe Systems Inc. and its widely used PDF format. Adobe publishes details about its format so anyone else can create compatible programs.

In Massachusetts, Gov. Mitt Romney’s administration has directed state executive offices to begin storing new records by Jan. 1, 2007, in an open, proprietary-free format called OpenDocument, in response to such concerns.

That’s been widely seen as a blow to Microsoft, whose Office line of word processing, spreadsheet and other business applications dominates the market.

Yates said the company is hoping to hear from the standards body in nine to 18 months.

The proposal is backed by companies including Apple Computer Inc., Intel Corp. and Barclays Capital, the investment banking division of Barclays Bank PLC.