This Standard is to provide the means for individual axial adjustment of drilling, reaming, and tapping tools, etc. in the spindles of single or multiple spindle heads. Further, its purpose is to permit interchangeability of adapters into different manufacturers' machines consistent with necessary accuracy. Its scope is primarily in the medium to large size of drill spindles, i.e. from No. 0 Morse Taper and .375 American Standard Taper through No. 4 American Standard Taper.