Original: Bombardier Transportation UK was formerly ADtranz, and before that ABB Asea Brown Boveri, who built the 1992 Stock currently used on the Central and Waterloo & City lines.
Simplified: Bombardier Transportation UK used to be known as ADtranz, and before that ABB Asea Brown Boveri. ABB Asea Brown Boveri built the 1992 Stock which is currently used on the Central and Waterloo & City lines.