Question about Mavlink::send_finish()

I start with apologies because I am far from literate with some of the intricacies of C++.
That being said, I am looking at the Mavlink::send_finish() member function in src/modules/mavlink/mavlink_main.cpp…
It makes a call to ::write(_uart_fd, _buf, _buf_fill);
Can someone tell me what this means??
What is the difference between ::write() and write()?
What “write” is actually being called?

To put whoever reads this at ease… yes, apparently I’m an idiot.

I also posted this question in a more general C++ form on stackoverflow.
The answer is here:

Based on that answer, I assume that ::write() is actually pointing to the global write() function within NuttX.