What Is Zero Error Of A Measuring Instrument ?

[DRACO]

I cannot come up with a correct definition and explanation for zero error.

 

 

Is this correct?
"The systematic error in a measuring instrument due to non-uniform or wrongly marked graduation due to which a measurement may be less or greater than actual measurement is called zero error of the measuring instrument".

Another one:

The measuring instruments are combination of two or more scales. The accuracy of these scales depend on each other. If these scales are not on zero level with respect to each other then zero error occurs. So we can say that:
"Th error which occurs in a measuring instrument due to non-levelling of scales on zero point is called zero error.

Edited July 8, 2020 by DRACO