The upcoming version of the GNU General Public License (GPL) may include modifications addressing Web applications and software patents, among other changes, according to Free Software Foundation founder Richard Stallman.

Stallman spoke of the upcoming GPL 3.0 in a lengthy interview with IT book publisher O'Reilly Media, which is holding the European Open Source Convention in the Netherlands next month.

He said that while the GPL is the most widely used open-source licence, it remains fundamentally misunderstood - its primary purpose being as a moral force protecting users' rights, rather than a model for successful software development.

"We often hear that some 70 percent of Web servers use Apache; what we don't hear is that a large fraction of those servers are using a non-free modified version of Apache, as permitted by the Apache license," Stallman said.

"In the free software movement, our goal is to bring freedom to computer users, and such an outcome for us would be a substantial setback." Unlike the GPL, Apache's open source (or free software) licence allows derivatives to be placed under different licensing terms.

The GPL is used by software - most notably the Linux operating system (also referred to as GNU/Linux) - that has become essential to businesses. But Stallman's moral stance has been known to make the corporate world somewhat nervous, one of the factors behind the creation of the business-friendly Open Source Initiative.

"The GPL gets its legal force from copyright law, but that is not a source of moral authority," Stallman said in the interview. "Copyright infringement is not necessarily wrong, but distributing software without respecting the freedom of the users is necessarily wrong."

Stallman and others are currently working on version 3.0 of the GPL, with slight modifications intended to address the current legal and technical environment. One change could address the use of GPL software by companies such as Google to offer their services online, Stallman said.

This could allow developers to require that users have the ability to download the source code for the software they are using online, Stallman said. The option would be available at the developer's discretion, but once put into force, would be required for future derivatives of the software. "This will not apply to all GPL-covered programs, only to programs that already contain such a command... developers could activate it in the future," Stallman said.

Another potential new clause could address the controversial subject of software patents. Under the current operation of the GPL, if a company owns patented techniques that it includes in a GPL-covered program, it is implicitly licensing the use of those techniques in the code as distributed.

The new licence may include an explicit statement of this, Stallman said. "The implicit license, we believe, only covers techniques used in the code as the distributor distributes it," he said. "We're not sure exactly what GPL 3 will say about this, but it won't be greatly different."

He criticised the Linux community for its response to offers by IBM and other companies for free use of some of their software patents by open source projects without risk of retaliation. Such a move is not acceptable, Stallman said. "What we should criticize is the implicit remaining threat to attack the rest of us, or attack us with the rest of their weapons," he said. "Where software patents exist, no software developer, no computer user is safe from them."

Issues the GPL itself can't address include hardware-based copy-protection modules, Stallman said.

The full interview is available on O'Reilly's Web site.