OGP accuracy specifications are expressed in the following form:

**E _{x} = [k + (multiplier * L) / 1000] µm**

Where:

**E**= the maximum measuring error, in microns, under the given conditions

**x**= 1, 2, or 3 referring to a linear accuracy, planar accuracy, or volumetric accuracy, respectively

**k**= systemic or inherent machine error that is not length dependent

**multiplier**= a constant that defines the travel-dependent error

**L**= the length of travel over which the accuracy specification is desired, in millimeters

**µm**= microns, the accuracy unit of measurement

In all cases, the result is +/-

OGP conventions for accuracy specifications:**E _{1}** is the linear accuracy in a particular axis - X, Y, or Z

**NOTE**: A specification shown as "E1 X,Y" with a comma delimiter between axes, means a linear accuracy specification that is the same in the X and Y axes

**E**is the accuracy within a plane, typically the XY plane.

_{2}**E**is the accuracy within an XYZ volume; sometimes referred to as volumetric accuracy.

_{3}