Let's say I have a root sheet, on which I have a child sheet, hierarchy wise, then on the child sheet, I place a GND component among other input and output lines.
Now I know I need to import pins on the root sheet for the child to connect input and output signals, but do I need to do it for GND?
Should I connect GND to a global GROUND label, that seems kind of stupid and wasteful to me, just like bringing out the GND pin onto the root sheet. I realize there might be multiple ground planes, but is that's what Reference and Value is for in the GND component?
Another question, in the GND component, value says GND but Reference says "#PWR?", what does the reference mean with that keyword, is it a macro of some kind?