Conversation

https://github.com/Microsoft/MS-DOS/tree/master/v2.0/source

"The user manual contains some significant errors. Most of these are due to last minute changes to achieve a greater degree of compatibility with IBM's implementation of MS-DOS (PC DOS). This includes the use
of "\" instead of "/" as the path separator, and "/" instead of "-"
as the switch character."

it's always kind of interesting when you encounter a fossil trace of someone's Giant Mistake as it happened.