The board of the Open Source Initiative (OSI) has approved two Microsoft licenses that allow proprietary source code to be shared, a move that is likely to inspire protest and spur controversy for die-hard open source proponents.

The Microsoft Public License (MPL) and the Microsoft Reciprocal License (MRL), two of Microsoft's "shared source" licenses, are now viable OSI licenses for distributing open source code alongside more widely used community licenses such as the GNU General Public License and the Mozilla Public License.

"Today's approval by the OSI concludes a tremendous learning experience for Microsoft, and I look forward to our continued participation in the open source community," said Microsoft general manager of Windows Server Marketing and Platform Strategy Bill Hilf in a press statement.

Microsoft submitted licenses from its Shared Source Initiative to the OSI in July, an announcement made at the O'Reilly Open Source Convention. The news was generally well received by top open source community leaders at the time, though some noted that a move from Microsoft to work with the community on open source licenses could have come a lot sooner.

The MPL and MRL are two of three licenses that Microsoft offers in its Shared Source Initiative, which it has offered for about five years as a way to share source code without having to work with open source organizations or companies. The other is the Microsoft Reference License, which is the most restrictive of the three and was not submitted for approval.

The MPL is the least restrictive of the Shared Source licenses, allowing licensees to view, modify, and redistribute the source code for either commercial or noncommercial purposes. The license also allows licensees to alter the source code they share with others as well as to charge a licensing fee for their work if they choose. The MRL, which the company recommends for collaborative development projects, carries specific requirements if licensees combine their original code with MRL-licensed code. It does, however, allow for noncommercial and commercial modification and redistribution of licensed software.

Red Hat executive Michael Tiemann, who also serves as president of the OSI, said Tuesday that while some in the community balked at the OSI accepting licenses from a company that historically has not been open source friendly, in the end, the licenses spoke for themselves. "They do have two licenses that went through the community process and did sustain the open source definition," he said.

However, this does not mean the process went entirely smooth. While Microsoft was cooperative and asked for no special treatment during the process, the OSI had to field about 400 e-mails from community members about the decision to let the company's licenses go through the approval process, Tiemann said. And the OSI already is experiencing backlash from open source proponents that are not happy with the approval of MPL and MRL.

"I've received three e-mails in the last hour from people who say, 'To heck with the OSI, you guys are just now pawns in Microsoft's game ... you have made a deal with the devil,'" he said. However, Tiemann believes the OSI had a responsibility to be fair and impartial in letting Microsoft submit its licenses.

"What would you think of a club that would say, 'We won't take any members that come from the city of Chicago, even if two people in Chicago meet the criteria for entry?'" he posited. "We said from the outset that we would be fair and, to be honest, some people said, 'No, you don't.'"

Microsoft has shown itself to be more cooperative with the open source community, even launching recently an open source Web site devoted to educating the community about its initiatives in this area and to showing how its proprietary technology can work with open source software. At the same time, however, company executives have been making bold claims about how much Microsoft intellectual property is contained in open source software such as Linux, and threatened to collect royalties on patents it owns in that software. These claims are widely viewed as a way to spread fear, uncertainty, and doubt among customers looking to adopt open source software as an alternative to Microsoft products.

Tiemann said it remains to be seen if any companies other than Microsoft will license code under MPL or MRL. However, he said if Microsoft plans to embed patented technology in software licensed under an OSI-approved license and "call it open source" -- as some open source proponents fear -- they had better think twice.

"If there is some experimentation on their side to see whether or not they can produce royalty-bearing open source code, I think they'll see that 400 messages is just the beginning," Tiemann said.