IBM was investigated for antitrust violations. After many years, they entered into a consent decree which required them to document all of their APIs. And not

IBM was investigated for antitrust violations. After many years, they entered into a consent decree which required them to document all of their APIs. And not just that - they were not allowed to have any hidden interfaces that might place IBM application developers at an advantage over non-IBM application developers. As long as you coded to the published API, you were good to go.