Licence transfers aren't the only thing the Eula (end-user license agreement) for Microsoft's Windows Vista OS limits. The licence also puts restrictions on how benchmarks of certain components of the OS (operating system) can be published, another issue that's raising eyebrows as Microsoft has still not clarified how changes will specifically affect users.

According to the Vista Eula, because the OS contains "one or more components" of the .Net Framework 3.0, users can conduct internal benchmarking of those components, but can't disclose the results of those benchmarks – or measurements to compare rival products – unless they comply with conditions found at a Microsoft website.

Several attempts to reach that website to see what those conditions are for benchmarking were unsuccessful last night, as the page for unknown reasons could not be displayed in Internet Explorer 7.0.

Several published reports and open-source proponents have raised concerns about this terminology of the Vista licence, claiming it limits the benchmarking of Windows Vista that can be published because of the inclusion of the .Net Framework. While benchmarking is still possible, Microsoft is in control of how that information is released, and the company can change the rules on the "conditions" website at any time. This could make it difficult for anyone to get a clear idea of how the OS and certain components perform, critics say.

"To be in control of what is published seems to be the logical consequence of Microsoft's policy," said Joachim Jakobs, a representative for the Free Software Foundation Europe. He cited several instances in which this behaviour around benchmarks is consistent with other efforts Microsoft has used to control the use of its software, such as its litigation against companies it says violates patents Microsoft owns, and the company's continuing antitrust tussle with the EU (European Union).

Microsoft said it will clarify issues raised by changes in Vista licensing tomorrow – including ones around benchmarking. User concerns over Vista licensing began several weeks ago, when it was disclosed that Microsoft is limiting the number of machines to which users can transfer licences to one as part of the changes.

The limitations on .Net Framework benchmarking are not new – they have been around since Microsoft introduced the development framework. But benchmarking and other limitations in Windows Vista brings to light a larger issue about the OS's licensing in general, said Michael Cherry, analyst at Directions on Microsoft in Kirkwood, Washington.

"My bigger issue with the licence in general is that it's just indecipherable," he said. "There are a lot of terms that are probably more important to me than benchmarking, but how do I find them among these obscure things that are unclear about what I can or cannot do?"