null
or not explicitly stating a value. option explicit sub main() ' { call xyz("one", "two") call xyz("apple") call xyz(param_2 := "banana") call xyz call xyz(param_2 := null) activeDocument.saved = true end sub ' } ' xyz { private sub xyz ( _ optional param_1 as variant, _ optional param_2 as variant _ ) if isMissing(param_1) then selection.typeText("param_1 is missing") else selection.typeText("param_1 = " & param_1) end if if isMissing(param_2) then selection.typeText(" - param_2 is missing") else selection.typeText(" - param_2 = " & param_2) end if selection.typeText chr(13) end sub ' }