ISO 129-1:2018 establishes the general principles for presentation of dimensions and associated tolerances that apply to 2D technical drawings in all disciplines and trades but which can also be applied to 3D applications.ISO 129-1:2018 does not cover the application of dimensional tolerances and their meaning. See ISO 14405-1 for tolerancing principles. This document can only be used to describe the nominal model of a drawing, not the non-ideal surface model (skin model) used for tolerancing purposes (for more information on tolerancing specifications, see the list of GPS standards listed as normative reference or as bibliography)Considering the ISO 14405 series, the presentation of tolerance indication is unambiguous when it is applied to a dimension which is a size and ambiguous when the dimension is not a size.All rules presented in this document are available for any type of drawing (see ISO 29845).In addition, this document introduces the concept of property indicators, developed length, between, surface indicators, flag notes and textual instructions.NOTE 1 All figures are shown in 2D views only.NOTE 2 Additional information and details for construction engineering are given in ISO 6284.