Abstract: A toolholder has a shank with a tapered body which is adapted to fit into a complementary socket in an end face of a machine tool spindle. A blind bore in the body is engageable by holding means for holding the shank in the socket. A first axial section of this bore is threaded for engagement with a threaded member of one kind of holding means such as a pulling rod or a set bolt coacting with pulling means. A second axial section of the bore is enlarged to form an annular groove for engagement by an expansible head of a pulling member of an alternative kind of holding means. An encoder ring is removably fixed at the toolholder. Each time the tool is exchanged the encoder ring is replaced by an encoder ring corresponding to the new tool.