ISO/TS 13399-303:2016 specifies a concept for the design of tool items, limited to solid (non-indexable) end mills, with the usage of the related properties and domains of values. ISO/TS 13399-303:2016 specifies a common way of design simplified models that contain the following: - definitions and identifications of the design features of solid (non-indexable) end mills, with a link to the properties used; - definitions and identifications of the internal structure of the 3D model that represents features and properties of solid (non-indexable) end mills. The following are outside the scope of this part of ISO/TS 13399: - applications where these standard data may be stored or referenced; - creation and exchange of simplified 3D models for cutting tools; - creation and exchange of simplified 3D models for cutting items; - creation and exchange of simplified 3D models for other tool items not being described in the scope of this part of ISO/TS 13399; - creation and exchange of simplified 3D models for adaptive items; - creation and exchange of simplified 3D models for assembly items and auxiliary items.