Sperate question about Time library's adjustTime function

Using Arduino Programming Questions
1

void adjustTime(long adjustment) {
sysTime += adjustment;
}

None of the documentation nor the source code really tells me this...

But what is adjustment?

Microseconds? Milliseconds? Seconds?

I would assume milliseconds.

2

Looking a the 'setTime()' function, it takes a 'time_t' parameter, then sets 'sysTime' to the value of that parameter. 'time_t' is the seconds since 1970.
Therefore, the adjustment in 'adjustTime()' will be seconds, not milliseconds.