Raymond Chen answers that: https://devblogs.microsoft.com/oldnewthing/20031022-00/?p=42073 https://devblogs.microsoft.com/oldnewthing/20031022-00/?p=42... DOS

Raymond Chen answers that: https://devblogs.microsoft.com/oldnewthing/20031022-00/?p=42073 https://devblogs.microsoft.com/oldnewthing/20031022-00/?p=42... DOS required extensions and most early DOS apps just always appended their own extensions automatically and only took in the base name. The system ignoring the file extension made it easier to use the devices in every DOS app, not just ones aware of the devices.