def __init__(self, kind="gas", volumeSpec=0.0, Specification=None, Assets=None, *args, **kw_args):
        """Initialises a new 'Medium' instance.

        @param kind: Kind of this medium. Values are: "gas", "liquid", "solid"
        @param volumeSpec: The volume of the medium specified for this application. Note that the actual volume is a type of measurement associated witht the asset. 
        @param Specification:
        @param Assets:
        """
        #: Kind of this medium. Values are: "gas", "liquid", "solid"
        self.kind = kind

        #: The volume of the medium specified for this application. Note that the actual volume is a type of measurement associated witht the asset.
        self.volumeSpec = volumeSpec

        self._Specification = None
        self.Specification = Specification

        self._Assets = []
        self.Assets = [] if Assets is None else Assets

        super(Medium, self).__init__(*args, **kw_args)