We present the Timing Definition Language (TDL), which supports the development of dependable embedded real-time systems. TDL is conceptually based on the time-triggered programming model introduced by Giotto but provides a more convenient syntax, more control over the timing of periodic activities, an industrial strength tool chain, and, most importantly, adds a component model and supports the integration of asynchronous activities in a time-triggered system. We present the introduced language concepts and outline the TDL-based tool chain, which also includes support for simulation, distribution, and automatic code generation. Finally, we show an example that uses some of the extensions and compare TDL with other extensions of Giotto.