Software freedom activist Richard Stallman made an unexpected appearance at a European Patent Office presentation in Brisbane today.

Stallman, pictured, who was also due to address the World Computer Congress later in the day, carried a placard that said: "Don't get caught in software patent thickets".

He briefly interrupted a presentation by European Patent Officer Ralf Abbing, who spoke about the "big issues in IP in relation to computing technology".

In his presentation, Abbing outlined the requirements for software patent applications under the European Patent Convention (EPC).

"We have a very narrow interpretation," Abbing said of patentable software.

According to Article 52 of the EPC, patented inventions had to be "susceptible of industrial application", new, and involve an inventive step.

The Article excluded aesthetic creations, discoveries, mathematical models, business methods and presentations of information from being patented.

Abbing explained that patentable software also had to be "technical" - that is, software that processed physical data parameters, controlled values of an industrial process, or affected "the way a computer operates".

As such, software that processed monetary values, defined auction rules, sold or booked packages, or defined promotional incentives could not be patented.

Eva Hopper, another patent examiner at the European Patent Office, said there were 300 examiners who dealt with computer software and hardware patents at the office.

In a separate presentation at the World Computer Congress, Hopper noted that innovators often made "significant investment" in developing new products.

Without intellectual property protections like patents, competitors could exploit this development work and marketing efforts, she said.

"Competitors see this product as successful and start building similar or even identical products ... at cheaper price, which will put pressure on the original inventor and eventually drive the innovator out of business," she said.

The presentations came as the Australian Advisory Council on Intellectual Property prepared a report on patentable subject matter, which would be released early next year.

Last month, a developer-led petition to abolish software patents in Australia attracted 1083 signatures.

Stallman said he supported the movement, and told iTnews that the European Patent Office was lobbying for software patents in Australia.

"We're here at the World Computer Congress and what I've discovered is that the European Patent Office is here to campaign in favour of software patents in Australia," he said.

"You can be sure that if Australia allows software patents, almost all the patents will belong to foreigners and will give them the opportunity to sue Australians.

"There's no problem that requires a solution with anything like software patents. Without software patents ... neither of us would get sued by the various patent troll companies whose sole business is collecting patents so that they could go threaten people."

Stallman was accompanied by another protestor and distributed printouts of his article about intellectual property being a "seductive mirage".