th3chainrule:
So that does not necessarily mean that there is something physically attached to A0 right?Such as an led.
The name implies that there is an LED connected to the pin, otherwise why use that name, but there may actually be nothing connected, as in the case where a floating analogue input is used as a seed for the randonSeed() function.
The name also implies that the pin is being used as a digital output because under normal circumstances you would not read from an LED. Although it is possible to use an LED as an input it would be unusual. Looking at the corresponding pinMode() command for pin A0 would make this clearer, but note that pins default to being inputs so there may not actually be a corresponding pinMode() command.