The concept of power can be viewed from different perspectives. In resource accounting (DIN 69902), the physical and technical definition is used: performance is work per time. In this context, performance means achieving a certain work result within a specified time frame. Such a definition completely disregards intellectual, above all creative and communicative achievements, which are not time-bound but dependent on their originator and not directly evident from the result produced. In the field of cost and activity accounting (DIN 69903), in terms of project management (DIN 69901) and also in progress control, the legal concept of performance prevails. It can be measured in a much larger scope, since it is defined only by doing or omitting, for a project e.g. in the context of a work contract. The respective control time (key date) has no mathematical, but only delimiting and limiting significance for performance. Often a legal performance corresponds to a technical work result. (Source: GPM)