SDIF STFT Spectra

{
	"1STF",			//	ID
	{			//  HEAD
		{"Freq sampling interval", "Hz", "%12.4f" },
		{"Frame size", "Seconds", "%5.3f" },
		0
	},
	{			//  MATRIX
	    "Bin",		//  ROW
	    {"Real", "unitless", "%8.4f" },
	    {"Imaginary", "unitless", "%8.4f" },
	    0
	}
}

The real and imaginary parts are unitless, as they come out of the STFT.

You can convert these complex numbers into polar form to get magnitude and phase.