Following the introduction of MTM-1 there were a variety of attempts at improvement. Developments were mostly concerned with speed of application and fell generally into two types. The first type of development was the construction of systems of elemental data for use in particular work areas, the second type was the construction of general systems of motion data of larger unit time value than MTM-1.
	During the 1960's, Dr. F. Evans, Technical Director of the MTM Association derived a set of principles relating to the optimisation of data. One of the most important principles produced was that for any work situation an analyst, as a first step, should establish one single class to which all activities can belong. The average time and variance for this single class should then be computed and its precision compared with the application conditions.
	The principal combined motion data systems, MTM-2 and MTM-3, were significant improvements on the MTM-1 system, particularly with regard to speed of application. However, they can be viewed simply as a result of MTM-1 methods correction exercises. In general, methods engineering has always held superiority over methods correction. This would indicate that the best way to develop higher level motion data systems, or any MTM system, would be to start from the first principles of data system design.
	PMT Core Data was developed as MTM Core Data and is the result of the application of these principles to the design of motion data systems.
	The aim of Core Data was to provide a predetermined motion time system which retained all the analysing power of the MTM-1 and MTM-2 systems and which could define the work cycle, whether constant or variable, with a single motion pattern.
	The solution is a pyramid of data containing some 1,500 elements in motion combination form that provides six levels of case descriptions and four levels of distance measurement. The single average motion pattern produced by a Core Data analysis is equivalent to that produced by many recordings of the same work cycle expressed in MTM-1 or MTM-2 terms.
	PMT Core Data is a predetermined motion time system, based on the MTM-1 and MTM-2 systems, which analyses any manual operation or method into the basic motions required to perform it and assigns to each motion a predetermined time standard which is determined by the nature of the motion and the conditions under which it is made.