Some of these definitions may seem rather idealistic, but this tough definition is seen as important to the effectiveness of this key step. Once value-adding work (actual work) has been separated from waste, then such waste can be subdivided into 'needs to be done (auxiliary work) but non-value adding' waste and pure waste. The clear identification of 'non-value adding work', as distinct from waste or work, is critical to identifying the assumptions and beliefs behind the current work process and to challenging them in due course.