The US Department of Defense is promoting the positive aspects of free and open-source software for use in sensitive and un-restricted government IT projects.

The department has highlighted six benefits to tackle what it called "misconceptions and misinterpretations" of the existing laws, policies, and regulations. The current rules were written in May 2003.

The DoD claimed that lingering issues have "hampered effective DoD use and development of OSS [open source software]," said the department's document, released Tuesday.

The department highlighted the confusion that surrounds open-source licenses and encouraged people to take the time to learn about the different licenses.

Specifically, it corrected the notion that use of open-source in software projects or modification of code would mean the government is then obliged to distribute its own code, that "OSS should not be integrated or modified for use in classified or other sensitive DoD systems."

"Many open-source licenses permit the user to modify OSS for internal use without being obligated to distribute source code to the public," the DoD wrote.

It points out that the GPL requires distribution of corresponding source code to the recipient of the software if the modified code is released.

DOD deputy chief information officer David Wennergren, who wrote the document, said: "For this reason, it is important to understand both the specifics of the open-source license in question and how the Department intends to use and distribute any DOD-modified OSS."

Like the rest of the US government and the private sector in general, the DoD has been a large user of open source. The White House, meanwhile, has also flown the flag for open-source in government.

Wennergren said DoD agencies must still conduct market search when procuring property or services, so they can't rule-out closed-source or proprietary software out of hand.

But he noted: "There are positive aspects of OSS that should be considered when conducting market research on software for DoD use."

Those positive aspects are practical and financial. On the former these center on the openness of the code, which means a continuous and broad peer review of the code, the unrestricted ability to modify the source code, rapid prototyping, reduced reliance on a single developer or vendor, and the fact that licenses do not limited access to use of the software.

On price, Wennergren pointed to the fact products build using open-source code do not use an expensive per-seat licensing model and that the open nature of the code means the maintenance load is spread, potentially reducing lower total cost of ownership. ®