A little help with voltage regulator basics: Line Regulation

[red913]

Here's the data sheet I'm looking at.
It specifies output voltage on a 7805 for typically 5V. Got it, exactly what I expect.
Then it says below that, "Line Regulation" is either typically anywhere from 2-50V depending on what's coming in.
So I guess I don't understand what line regulation really is. To me line regulation sounds like you're just regulating the voltage coming into the regulator...but the output voltages they show on the data sheet vary so widely,which defeats the purpose of a regulator in my opinion. Clearly that's not the case though, as people wouldn't use these otherwise. .So what am I missing here?

 

[(*steve*)]

That's 2 to 50 millivolts (thousandths of a volt) that the output will vary as the input voltage changes within the specified levels

 

[red913]

oh dang...I didn't even notice the unit column! ok, thanks.

 

[kpatz]

"Line regulation" specifies how much the output voltage will vary when the input ("line") voltage varies.

"Load regulation" specifies how much the output voltage will vary when the load current varies.