1. A method of managing a process model history having a plurality of process models stored therein, the method comprising: organizing the plurality of process models according to a combination of a first priority criterion and a second priority criterion, wherein each process model is represented according to a combination of a value in connection with the first priority criterion and a value in connection with the second priority criterion; calculating a degree of separation between each of the organized process models and a point of reference common to each of the organized process models, wherein the point of reference comprises a value in connection with the first priority criterion and a value in connection with the second priority criterion; and removing a process model from the model history based on the degree of separation if, prior to removal, a total number of process models identified for the same control routine as the process model to be removed exceeds a threshold value in connection with the total number of process models identified for a control routine.