The auto allocation process is triggered when a new demand for allocation arise or at goods receipt when there is new stock that can be allocated. The trigging, which can be executed from a number of functions listed in the database model, is done by writing a record to the work table MMM920.
The (MMM920) work table is then read by the auto start job 'Auto Allocation' (MMS920) which monitors reservations in the material plan (see (MMS080)) for items that should be automatically allocated. The auto allocation sequence could be by planning date or by order priority and then planning date depending on the setting of 'Auto allocation sequence' (MMS005/G). Auto allocation is performed for reservations inside the demand time fence (see (MMS002/E), (CRS701), and (MMS005/G)) if they are qualified according to the allocation method stated in (MMS002/G).
Further, (MMS920) calls (MMS921) where it is decided what stock to allocate. In an attempt to simplify the process, one could say that (MMS920) decides which orders that should get the stock and then (MMS921) is called to decide which balance identity that should be allocated.