Answer:  When the users have a part set with the Order Action Policy (OAP) of "Lot for Lot" MRP will provide suggested actions per each requirement, in this setting the MRP will ALWAYS apply the Pref Code rule (See Article #943 for further detail on the Pref Code rule).    But, then when a part happens to have the OAP set to "Daily, Weekly, Monthly, etc..." the calculation of the suggest MRP actions become more complicated.  In aggregation mode, there may be a number of different requirements all for the same exact part.  And those requirements may be spread over some period of time, e.g. one week.  In the weekly OAP, we will accumulate all of the different demands for the part, and present an order action for the sum total of that parts requirements, setting it due for the earliest day of the week selected in the system setup.

 

SInce the requirements for the same part may have different AVLs for different demand, as generated from different customers and different BOM's, and there may not be one AVL that is common to all demands.  When this happens, MRP performs an analysis of these AVL requirements and determines what the best mix of AVL's and quantities would be to most efficiently satisfy the diverse AVL demands.  This results in selecting the AVL that has the most universal application to the requirements as the greatest number of parts needed.  Next the demands are searched for remaining AVL demands (those not satisfied by the first round), and performs the same analysis for that AVL, resulting in an order demand to also by X quantity of the next AVL.  If there are still any demands that are not covered by the first two AVL's selected, the process is repeated until all demands are covered.  The result may end up that in order to meet the specific AVL demands for a variety of customers and BOM's several AVL's are ordered with varied quantities for the same internal part number.

 

In doing this calculation, and in order to provide the most efficient buying information, we could NOT include the AVL preference considerations.  It would defeat the purpose of maximizing the order efficiency and minimizing the number of parts orders.  But remember, this is NOT the issue, when "Lot for Lot" aggregation is selected for the parts, then the order preference takes precedence.

 

If the preferred AVL quantity needed for a period (day, week, month, etc...) is exactly equal to the largest quantity for any other AVL for a part, the program will substitute the preferred AVL for any other AVL and only in that case.  If the quantities are not equal, then our optimization algorithm will apply as explained above.

 

 Note: If the part is on a Customer BOM and assigned to that Customer then the Preference's from the Customer part number will dictate how other modules within the system (MRP, Purchasing, Kitting, Allocations) determine what is suggested or defaulted into the screens.