Microsoft is promising that it will negotiate to license patents, rather than resorting to the courts - in a barely-disguised stab at Google, which made its own patent promises yesterday too.
The company says that trying to block infringing products from sale only serves to damage the industry.
It says it won't seek injunctions or exclusion orders on the basis of patents, and will make themavailable for license without demanding cross-licensing deals in return, unless the patents are essential to the same industry standard.
And it won't, it says, transfer standard essential patents to any other firm unless it agrees to stick to the same rules.
"A promise to license patents on reasonable and nondiscriminatory terms, absent these three points, is an empty promise," says Dave Heiner, vice president and deputy general counsel for Microsoft's Corporate Standards Group and Antitrust Group.
Heiner cites Apple and Cisco as operating by similar rules - but, notably, not Google, which yesterday wrote to standards boards about the thousands of patents it expects to get its hands on as a result of its merger with Motorola Mobility.
The letter promises simply to continue licensing patents on a fair, reasonable and nondiscriminatory (FRAND) basis.
However, according to patent expert Florian Mueller, Google's promises are so vague that, they 'make a mockery' of the FRAND concept.
On royalties, he points out, Google reiterates Motorola's policy to demand 2.25 percent of the net selling price of the end device. Otherwise, it says, injunctions will follow. And pending litigation won't be withdrawn.
"Seriously, this letter fails to address any concern any regulator may have. I can't see that this paves the way for the deal to go through in the short term," says Mueller.
"To me it looks like Google is taking an extreme position now so it can easily make concessions going forward."