Over 90% of the personal computer operating systems in the world are Windows. As a result, application developers often use Microsoft tools to help write programs that work with Windows, and with related technologies or products that are integrated or often used with Windows. Microsoft has a history of using its tools to lock out other products. For example, Microsoft web development tools have often resulted in code that only works with IE. The application developers may or may not even be aware of this. They use a convenient tool provided by the operating system vendor, and end up helping extend the operating system monopoly to other products.
Examples of tools to which this principle would apply include Microsoft Expression Web and Microsoft Office Sharepoint. One might also include Silverlight and related development tools, or tools that do things such as embed MS Office documents in web pages.
This principle asserts that Microsoft cannot cause web or application developers to create IE-specific content by default.