Process Manufacturing Actual Lot Cost Process

 I am looking for white papers with detailed logic on how the actual lot cost process works and how.  We are having difficulty understanding how the Lot Cost Details populate, eg. the date used on the Lot Cost Detail for the Cost Date, how it is possible to have more than one Final Cost for a Lot Cost Detail as examples.  The OPM Cost Management Documentation does not have enough detail on how the costing process runs and how the costs are populated.