Abstract: A method for the preparation, editing and maintenance of tool data sets for machining processes in an NC control system has at least one tool data organization that is separate from the control and is stored in the memory of an ADP system. The tool data organization has tool data sets for tools that for each of the tools to be used has the space for static and dynamic data. The tool data organization has separate list data sets of a machining process that can each contain a reference to the associated tool data set, and the required list data sets are taken over and stored in memory, together with the associated tool data sets, for process execution in the NC data processing unit. At least the dynamic data of the tool data sets can be updated in accordance with the current NC machining processes.