Matrix / Runout

矩阵与内圈刻字 (Matrix / Runout) refers to manufacturing markings found outside the playback groove of a record or on the reflective ring at the center of an optical disc. On vinyl records, this area is commonly called the “runout,” “dead wax,” or simply “wax,” while on CDs and other optical discs, the matrix string and other codes are displayed at the inner edge of the data area. These markings can be hand-engraved, machine-stamped, laser-etched, or formed during the injection molding process.

Historically, the matrix number on records was originally used to identify the master recording and was often associated with specific tracks, sides, and recording takes; once a master was selected to create a master cylinder, the number would appear on mass-produced records. Later, the inner ring of vinyl records might also include the cutting engineer’s signature, the cutting serial number, the master and pressing generations, the pressing plant’s mark, and copyright text. Different pressings of the same catalog number may have different runouts depending on the cutting or manufacturing batch. CD matrix numbers are typically written onto the glass master or during the mastering process and may include the client’s order number, catalog number, master version, and factory internal codes. The IFPI SID system, promoted after the 1990s, further distinguishes between the Mastering SID Code and the Mould SID Code: the former relates to laser mastering equipment or master disc facilities, while the latter identifies the mold or pressing facility during the replication stage. The positions and typography of these two SIDs often differ, and they are not synonymous terms for the matrix string.

The Matrix / Runout and the packaging catalog number are on different levels. Catalog numbers are managed and issued by record label, while matrix and inner circle codes primarily originate from the recording master, disc cutting, mastering, and replication processes; although certain strings may repeat the catalog number, this does not imply that the two are identical. Barcodes and ISRCs also do not replace manufacturing identifiers.

These identifiers are often used to distinguish pressing variants that are identical in appearance and track listing, but interpreting them requires knowledge of the specific coding conventions of the record label and the factory. Characters may be blurred, mirrored, accompanied by geometric symbols, or scattered in different locations; handwritten `1`s, `I`s, and letters can also be easily confused. A single code is usually insufficient to verify authenticity or identify the audio master; a judgment must be made by considering the disc surface, label, copyright line, SID code, and known manufacturing information.