navigation - How Many Tabs are Too Many?

The mockup below, has a screenshot of a software I stumbled upon last week. It grabbed my attention that it presented information in the following way. It had Many Interface Level tabs, inside those, it had many Major level tabs, that contained many Minor tabs. I want to stop there, because it gets confusing. What I want to know if how to reduce complexity by reducing the number of tabs presented for the user. The system itself is complex, but I'm pretty sure there should be better ways of presenting information.

The information above and the mock-up below might seem insufficient, however, it might give you an idea of the problem.

The application is window based (no browser).

^{download bmml source – Wireframes created with Balsamiq Mockups}

One quick solution I see, would be eliminating Interface level tabs and creating separate windows for those specific interfaces. But then I wouldn't like to have that many Major and Minor level tabs.

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Is there any usability standard that would suggest the wise use of tabs?

Answer

The problem with tabs within tabs is mostly visual, not logical. The situation you describe has three navigation levels - that's not that uncommon. If you make the different navigation levels look different from one another, you'll find that the perceived complexity is reduced.

^{download bmml source – Wireframes created with Balsamiq Mockups}