How to interpret line regulation of LDO expressed as percentage per volt?

[Jim from Chicago]

I'm reading the datasheet of an LDO and it says under line regulation 0.03%/V. The output of this LDO is 2.8V. Do you just multiply 0.03 * 2.8V to get 84mV?

I'm having trouble because I'm trying to compare this part against another part, and the other part expresses line regulation in plain milliVolts. This other part just says "2mV typ" for line regulation. How do I compare these parts?

[TimFox]

"Line regulation" is a misnomer that has been used for years.  Nothing regulates the line or the input.  Modern nomenclature is closer to "source effect" or similar.  The sibling of "line regulation" is "load regulation", the change in output voltage with load current.
It really means the effect of (change in the input voltage) on (change in the output voltage).
0.03%/V means that if the voltage at the input pin changes by 1 V (within the usable input voltage range), the output voltage will change by less than 0.03% of the nominal 2.8 V output, or 0.84 mV.  Since the operating range at the input is > 1 V, the range of output voltages over all possible operating input voltages will be higher.
The other part is poorly specified if your quotation is the complete statement, but probably means that over the specified "operating" range of input voltage, the output will change by < 2 mV typically, but not guaranteed.

[Jim from Chicago]

The full specification for line regulation for the other part is (Vin = Vout + 1V to 12V, Iout = 10ma).  2mV typ, 20mV max.

Thanks I think I'm getting a better grasp of it now.

[rstofer]

Can you breadboard an example circuit and then vary the input voltage while measuring input and output voltages?  Lab experiments explain so much!

[Benta]

The full specification for line regulation for the other part is (Vin = Vout + 1V to 12V, Iout = 10ma).  2mV typ, 20mV max.

Thanks I think I'm getting a better grasp of it now.

That means that at an output voltage of 2.8 V, input voltage is 3.8...14.8 V for the "line regulation" specification.