回複：我舉手，Pjiang 老師，小白兔老師，我有個問題。

Basically, it is right. The processing date is about your RD. But processing date is just a guideline. It is not accurate. In processing 485, USCIS will most likely following RD, that's the order they receive your case. But to give you GC, they will look at your PD.

PD by definition, please read why77's reply.

Don't need to worry about blank on PD column. It is normal.