ISO/TS 13399-312:2016 specifies a concept for the design of tool items, limited to any kind of reamers for indexable cutting edges, together with the usage of the related properties and domains of values. ISO/TS 13399-312:2016 specifies a common way of design simplified models that contain the following: - definitions and identifications of the design features of reamers for indexable cutting edges, with an association to the used properties; - definitions and identifications of the internal structure of the 3D model that represent the features and the properties of reamers for indexable cutting edges. 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 part of ISO/TS 13399; - concept of 3D models for adaptive items; - concept of 3D models for assembly items and auxiliary items.