New ISO standards on terminology are in preparation. These standards will probably define the following:

feature of size geometric shape defined by a linear or angular dimension which is a size (cylinder, sphere, two parallel opposite surfaces, cone, wedge) integral feature: surface or line on a feature

derived feature centre point, median line or median surface derived from one or more integral features

nominal integral feature theoretically exact integral feature as defined, for example, by a technical drawing

nominal derived feature centre point, median straight line or median plane derived from one or more nominal integral features (former: nominal centre point, nominal axis, nominal median plane)

real surface of a workpiece set of features which physically exist and separate the entire workpiece from the surrounding medium

real (integral) feature integral feature part of a real surface of a workpiece limited by the adjacent real (integral) features

extracted integral feature approximated representation of the real (integral) feature, obtained by extracting a finite number of points from the real (integral) feature; this extraction is performed in accordance with specified conventions (several such representations may exist for each (integral) feature) (former: actual surface, actual surface line)

extracted derived feature centre point, median line or median surface derived from one or more extracted integral features (extracted axis, extracted median surface) (former: actual centre point, actual axis, actual median surface) associated integral feature: integral feature of perfect form associated with the extracted...