Microsoft's decision to call its next operating system 'Windows 7' has prompted hundreds of observers to dispute the name.

The company has now tried to explain the thinking behind the decision in a new blog post, but its followers are still not satisfied.

Mike Nash, corporate vice president of Windows at Microsoft, explained in a blog posting yesterday that Windows 7 was chosen to keep things simple. "This is the seventh release of Windows, so therefore Windows 7 just makes sense," he wrote.

But hundreds of comments immediately posted in response to Nash's announcement showed that he had disturbed the Windows community, who could not understand how Microsoft got to the number '7'.

In a second posting today Nash has tried to explain the reasoning. "We see Windows as our next logical significant release and seventh in the family of Windows releases," he wrote.

Nash explained that the first three releases of Windows were labelled Windows 1.0, Windows 2.0 and Windows 3.0, and the fourth was a 'family' release encompassing Windows NT, Windows 95, Windows 98, Windows 98 SE and Windows Millennium.

The fifth Windows family included Windows 2000 which was codenamed 5.0, and Windows XP which was shipped as 5.1. Nash explained that the code version numbers had remained in order to keep application compatibility.

Windows Vista was version 6.0, Nash said, adding that Microsoft had realised from this launch that changing basic version numbers can cause application compatibility issues.

"[So] we decided to ship the Windows 7 code as Windows 6.1, which is what you will see in the actual version of the product in cmd.exe or computer properties. "

However, readers of Nash's blog have argued that Microsoft is confusing its product labelling strategy.

"What matters is the mismatch. No one is liking the mismatch," said a post by 'Someone'.

Another reader, known as 'MacG467', added: "I'd like an explanation where Windows NT 4.0 comes into play then."

A commentator under the name of 'Stanyau' suggested that Microsoft will create problems for itself down the line owing to "product vs. codebase" numbering disparity.

"Will Windows 8 The Product (which one assumes may be a big architectural rewrite similar to Windows 2000/Vista) be versioned as v7.0?" he asked.