Time stamp in MRP list after MRP Run

Hi Gurus

After running a MD01-MRP at scope of planning level, with processing key as NETCH, materials which had no planning file entry also were updated with the latest executed MRP run time stamp in MRP List MD05.

Is it the standard behaviour? As per my understanding, the materials with no planning file relevant change is not included in the MRP run with processing key NETCH/NETPL. Then how does the time stamp be relevant for the latest MRP run while the material was never included in the mrp itself?

Regards

Deepak Prasanna S