Customatrix was a wholly-owned subsidiary of Columbia Records and CBS, Inc. that produced masters, mothers and stampers for all of the regional pressing plants that were part of Columbia's North American operation, including the Terre Haute, Pitman, Santa Maria, Carrollton, and Bridgeport facilities in the US, and the Don Mills plant in Ontario, Canada.
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Since Columbia Records also pressed records for many other major record labels besides Columbia, including Elektra, Reprise Records, A&M Records, Epic, Warner Bros. Records, Harmony (4), Blue Thumb Records, Mercury, and many more, the Customatrix stamp can sometimes be found on these pressings as well.
Identifying Customatrix metalwork on vinyl pressings from any of Columbia's pressing plants is accomplished by locating a small stamped 0, ᴑ (sideways "0"), o, º, or °. This stamp should not be confused with the "0" used by Capitol Records Pressing Plant, Jacksonville, nor with the large "α" of Allied Record Company. It is often positioned either directly before or after the matrix number, though sometimes it will be stamped in a different location within the runout area. This stamp varies in size, and its design tended to fluctuate over time and varied in subtle ways. Customatrix is not necessarily associated with any specific matrix prefix such as XSM.
It should be noted that in many cases, locating the Customatrix stamp can be rather difficult, requiring the aid of a good magnification tool and strong lighting conditions. Often the stamping will be so faint that it looks more like a "C", "G", "J", "D", or a tight spiral; often, the mark appears to be made of tiny linear dots. In some cases the stamping can be so vague that it's just not possible to detect it at all. Since many contributors overlook this mark when entering the runout data from their copy into the BAOI, it's a good idea to mention it in the submission notes when the marking can't be found. That way others will know it's not just an oversight.