def __init__(self, typ=None, intensity=0, size=0, gen=0, cho=0):
        self._type = typ #"n1", "n2", "bg", "ch", "ge"
        if intensity<0 or gen<0 or cho<0 or size<0 or intensity>1 or size>1 or gen>1 or cho>1:
            raise ValueError ("Invalid Values for Structure Part")
        self._intensity = intensity # [0-1]
        self._size = size # [0-1]
        self._genover = gen # [0-1] overlay of general type lines
        self._chover = cho # [0-1] overlay of chorus type lines