1. A method of creating a requirement description for an embedded system, including an electronic control unit, comprising: storing a vocabulary of natural-language, selectable text segments in a data processing system, said text segments being combinable with one another to form at least one natural-language sentence, forming a machine-readable requirement description wherein each text segment is linked to a set of further text segments that can be combined with it, whereby for a text segment that is selected, the data processing system automatically represents the further combinable text segments in selectable form on a display unit.