In 1977 Gerhard Pahl and Wolfgang Beitz published Konstruktionslehre, a handbook of engineering design. Through many new editions it is still a standard work, and it has been translated into seven languages. Its method begins with Klären der Aufgabenstellung, clarifying the task. The result of this phase is a written requirements list, the Anforderungsliste. The phases of concept, layout and detailed design come after it. The engineering guideline VDI 2221 also begins with clarifying the task. In its 1993 edition, this is the step in which the requirements for the product are defined.