Using an external regulated 5vdc supply

I need to know if I can power an Arduino Mega by supplying regulated 5vdc to the pin on the mega marked 5vdc? - I realize that this is the output of the mega regulator when it is supplied via the usb connector OR the vin pin. Assuming that I do NOT plugin in the usb cable, and I do not supply un-regulated power to the vin pin then again, can I power the mega by supplying regulated 5vdc into the 5vdc pin?

And yes, I've read the following ambiguous description:

"5V. The regulated power supply used to power the microcontroller and other components on the board. This can come either from VIN via an on-board regulator, or be supplied by USB or another regulated 5V supply."

In the comment above - WHERE would you plugin "another regulated 5v supply"? At the input of the usb connector? It's either that or the 5vdc pin. It's NOT the vin pin because you need to supply at least 7vdc there because it feeds the onboard regulator.

need to know if I can power an Arduino Mega by supplying regulated 5vdc to the pin on the mega marked 5vdc?

Yes.
Either put it in the +5V pin, or plug it in using a USB charger or special USB lead supplying 5V & ground only.

Thanks for such a clear reply!