This document specifies requirements for indicating linear sizes. This document establishes the default specification operator (see ISO 17450-2) and defines a special specification operator for linear sizes. This document is applicable to the following features of linear size (see ISO 17450-1): — cylinders; — spheres; — two parallel opposite planes. This document provides a set of tools to express several types of linear size characteristics. It does not present any information on the relationship between a function or a use and a linear size characteristic.