Boeing procedures
A 737 can come with hundeds of options all dependant on the operator.
While flying as a passenger on a Delta 738 I observed the de/anti icing procedure take place with the slats and flaps set for takeoff, on competion they were retracted for taxi. I asked the Captain about it and his reply was after the merger with northwest they adopted this procedure to have conformity acrooss the merger. I know several operators that still de-ice with flaps/slats retracted. So my question is, can an operator have its own procedure as long as Boeing sactions it?
The answer would have to be yes.
And if so what then are Boeing procedures? What you know as boeing procedures may just be your operators choice of options on a boeing aircraft.