Thank you. It seems that the dividend reinvestment program is composed of two processes operating in parallel. The book keeping for the dividend payments and kind of an open ended stock purchase plan in which the broker has an "open, non-numeric specific" authorization to purchase shares in a manner timely to use the cash dividend payment for trade settlement. I can get my head around that and your description of the process as an allocation of the brokerages holdings fills some gaps.
The problem I am left with is why did they change from the dividend payable date about 18 months ago. I cannot find anything to cause the change.
Thank you for your conversation. I will mark this as answered. If you happen to ponder this further, please comment again. If I ever get an explanation, I will add that.
