This part of ISO/TS 13399 specifies a concept for the design of tool items, limited to any kind end mills for indexable inserts, together with the usage of the related properties and domains of values.This part of ISO/TS 13399 specifies a common way of design simplified models that contain the following:— definitions and identifications of the design features of end mills for indexable inserts, with an association to the used properties;— definitions and identifications of the internal structure of the 3D model that represents the features and the properties of end mills for indexable inserts.The following are outside the scope of this part of ISO/TS 13399:— applications where these standard data may be stored or referenced;— concept of 3D models for cutting tools;— concept of 3D models for cutting items;— concept of 3D models for other tool items not being described in the scope of this International Standard;— concept of 3D models for adaptive items;— concept of 3D models for assembly items and auxiliary items.