The filler and fillerOptions a chosen preset and a surface's own settings amount to — what ICellRange.autoFill is handed.
filler
fillerOptions
Optional
A fit refuses a step and a stop, and a filler that cannot fit refuses the fit itself, so neither is passed where it means nothing — a surface hiding those fields makes that displayed where this makes it true.
The
fillerandfillerOptionsa chosen preset and a surface's own settings amount to — what ICellRange.autoFill is handed.