This is a tolerance which is usually specified for cylindrical parts.
When rotating around a reference axis, the deviation of a measured value must not leave the tolerance field defined by two concentric circles.
The two concentric circles are perpendicular to the specified reference axis.
The distance between the two circles is described by the value given together with the sign for radial runout.
The tolerance described in this way is called radial runout.
During one revolution around the reference axis, the specified radial runout must not be exceeded.
In addition, the tolerance zone can be defined by two parallel planes.
These are perpendicular to a specified reference axis and have the specified distance to each other.
In this case, the tolerance is also called axial axial runout.
During one revolution around the reference axis, the axial runout must not be exceeded.