$_ = SETOPTION("CaseSensitivity","ON")

$NAME = "Ändern,Wäsche,Überraschung,überwintern"

while    INSTR($NAME,"ä") or INSTR($NAME,"ö") or INSTR($NAME,"ü")
      or INSTR($NAME,"Ä") or INSTR($NAME,"Ö") or INSTR($NAME,"Ü")
      or INSTR($NAME,"ß") or INSTR($NAME," ")
    SELECT
        CASE INSTR($NAME,"ä")
            $NAME = replace($NAME, "ä", "ae")
        CASE INSTR($NAME,"ö")
            $NAME = replace($NAME, "ö", "oe")
        CASE INSTR($NAME,"ü")
            $NAME = replace($NAME, "ü", "ue")
        CASE INSTR($NAME,"Ä")
            $NAME = replace($NAME, "Ä", "Ae")
        CASE INSTR($NAME,"Ö")
            $NAME = replace($NAME, "Ö", "Oe")
        CASE INSTR($NAME,"Ü")
            $NAME = replace($NAME, "Ü", "Ue")
        CASE INSTR($NAME,"ß")
            $NAME = replace($NAME, "ß", "ss")
        CASE INSTR($NAME," ")
            $NAME = replace($NAME, " ", "_")
    ENDSELECT
loop

? $NAME

Function Replace($String,$SS,$RS)
	$Replace=Join(Split($String,$SS),$RS)
EndFunction