D=/FLOAT=D_FLOAT (OpenVMS VAX)
                                   D=/FLOAT=G_FLOAT (OpenVMS Alpha)
                                   D=/FLOAT=IEEE_FLOAT (OpenVMS I64)

  Selects the default format for REAL and DOUBLE data types.   You
  must  specify  'floattype' if you use the /FLOAT qualifier.  You
  can specify the following float types:

   o  D_FLOAT with corresponding [FLOAT(D_FLOAT)] attribute

   o  G_FLOAT with corresponding [FLOAT(G_FLOAT)] attribute

   o  IEEE_FLOAT with corresponding [FLOAT(IEEE_FLOAT)] attribute