Conectiva, one of the four members contributing to the upcoming UnitedLinux operating system distribution, has moved to reassure developers that the consortium is following standard open-source practices, despite the introduction of a "closed" test version of the software.

UnitedLinux recently began circulating a beta-test version of its distribution to select partners, and is planning to make the software available for free public download later this month. For the "closed" beta test, users signed a non-disclosure agreement forbidding them from sharing information related to the software.

But such practices immediately set off warning bells in the open-source developer community, where many companies--MandrakeSoft is one example--publish software as soon as it is out of development. Much of the Linux operating system is based on the GNU General Public License, which requires software to be made freely available.

Last week, Bradley Kuhn, executive director of the Free Software Foundation, which protects the interests of the GPL, issued an open letter to the UnitedLinux Board of Managers requesting that the group be more open about the way it is approaching licensing issues. "Since nearly all of the volunteers from the Free Software community (your fellow developers) did not receive a copy of the so-called 'closed beta', we ask that in a show of good faith, you make available at least the terms of distribution you used for that product," Kuhn said in the letter. "Even as you release your new product to the public, the past situation must be clarified."

In response, Conectiva late on Friday published the terms of the non-disclosure agreement. It states that users may not redistribute the software "unless such information can be shown by documentary evidence to be in the public domain."

"As such, a counterparty has the right to refer to the GPL and freely redistribute any GPL copyrighted code," the company stated. "Further, the beta software itself makes numerous references to the GPL; and was distributed with both the binaries and the source."

Conectiva said that UnitedLinux did not consider it had done anything against the spirit of open-source development by using a closed beta-test program. "We consider this a natural part of UnitedLinux internal development," the company stated. Conectiva's letter and a link to the NDA can be found on the company's Web site.

UnitedLinux is not the only Linux organization bringing some business aspects of proprietary software into the open-source world. Red Hat, for example, is releasing an "Advanced Server" product that will not be as easy to obtain and install for free as its other distributions. While all the components will be freely available, the specific configuration of Advanced Server will only be available for a fee covering the cost of extra software features and support.

The four UnitedLinux members are Brazil's Conectiva, SCO Group of the United States, Turbolinux, now owned by a Japanese company, and Germany's SuSE Linux. The four companies will sell a single, SuSE enterprise software-based distribution in their own geographic areas, with additions from the other companies.