C isn't necisarily Canon here
I have a C40 from Blacks (rather had - it just died last week) It was souced from a thrift - Value Village for $1, so lack of documentation for it wasn't a problem.
It was a hot shoe flash that also came with a detachable 6" pc socket cord. When the pc cord was plugged into the flash the hot shoe contact was disabled.
It had a manual setting, with a guide number in feet at 100iso of 80, and also had two auto ranges using the on flash photosensor. There were (at 100iso) for f/56 and f/8 as I recall- not too useful, being just a stop apart. The C40 also did not have any sufficient light confirmation.