relativeDateTime(0, "year") returns?

Does relativeDateTime(0, "year") return today's date or the first day of this year?

The documentation is unclear.

Gets a timestamp relative to the current time.

If I offset the current time by 0 years, I should be left with the current date? yes?

The example usage provided by @flamber in this thread adds further ambiguity.

Just to be clear I'm not calling out @flamber - he has help this community so much. I'm asking for more clarity in the documentation for relativeDateTime.

Thank you.