The substrate interface was an interface system in Soong-type androids. This system was one of the main sections of the androids, along with the positronic cortex unit, the spatial orientation unit, the primary system module, and the locomotion subsystems. In 2365, when Commander William T. Riker was reviewing the technical specifications for Lieutenant Commander Data, this interface system was mentioned in the specs. (TNG: "The Measure Of A Man" )