Hi,
Read this article create by the expert Caetano Almeida. He explains what is the rescheduling:
What is rescheduling and how does it work - ERP Manufacturing (PP) - SCN Wiki
Now let me answer your questions:
1- Is the MRP routine who creates the rescheduling date and exception messages.. not MD04..
2- When a planner see a reschedule date and an exception message, the planner has to review the message and try to move the order if its possible.
Whenever the MRP finds a requirement, it checks if this requirement can be covered for an existing fixed receipt (within the rescheduling horizon), before creating a new replenishment element (planned order). This procedure is called “rescheduling check”.
If a fixed replenishment element is found, an exception message is created, suggesting the user to reschedule this fixed element in order to cover the shortage.
Kind Regards,
Mariano