Whether the call names a plot function with an add parameter (PlotFunctionsWithAddParam), and if so whether its add argument says that it appends to the existing plot, and undefined for any other function.
add
undefined
Whether the call names a plot function with an
addparameter (PlotFunctionsWithAddParam), and if so whether itsaddargument says that it appends to the existing plot, andundefinedfor any other function.