SMC refers to Sony Disc Manufacturing's manufacturing plant in Toronto, ON, locally operated by Sony Music Entertainment (Canada) Inc. (and later incarnations). The plant was originally established in 1976 by CBS Inc. (see Columbia Records Pressing Plant, Don Mills, ON) and was run by Columbia Records of Canada, Ltd. / CBS Records Canada Ltd. until January 1, 1991. CD manufacturing began in 1994.
In 2004, Sony Disc Manufacturing unified all international manufacturing facilities (excluding Japan) under the Sony DADC moniker, after which time the plant was run by Sony DADC (Canada) Co./Sony DADC (Canada) Inc. The plant was eventually closed in 2011.
Also commonly credited in the disc matrix as Sony Music Canada.