Ostu,
The database read period specifies the period in which capacity requirements are read from the database. All requirements are accessed which are partially or completely within the database read period.
The evaluation period specifies the period over which data is formatted and displayed.
The evaluation period must lie within the database read period.
The planning period defines the period in which the SAP system can carry out planning.
The planning period is smaller than or equal to the evaluation period. You cannot move operations outside the planning period. Equally, when automatic finite scheduling is carried out for an operation the system only searches for a new date within the planning
period.
The date for dispatching the backlog is of importance in period-related planning.
We use the date for dispatching the backlog to determine the date backlogs are to be
allocated.
Let us see an example for database period In above if you enter Entry type as G which is number of calender days and current date is 17th Sep and You have start date as -10 and Finish date as 30 then this generates database read period from 7th Sep to 7th Oct it means during capacity levelling with above setting all requirements which are falling in between above dates are only read from database.
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