How Microsoft DVD Navigator Selects the DVD Region

The Microsoft DVD Navigator uses the following method to determine region match while playing DVD discs on a PC:

The DVD Navigator gets the disc's region, drive's region and decoder's region. If the disc region is "all regions" then the DVD Navigator plays the disc. If the disc is not marked for all regions, the DVD Navigator checks whether the decoder has a preset region. If the decoder has a preset region and it does not match the disc's region, the DVD Navigator will return an error indicating that it cannot play the disc on the current DVD configuration. If the decoder's region is the same as the disc's region, the DVD Navigator will then check whether the drive's region is the same as the disc's region. If they are the same, the DVD Navigator will play the title. If they are not the same, then the DVD Navigator invokes the code to change the drive's region. If the allowed number of region changes has been exhausted, then the region change attempt fails and the title can't be played on that system.