  The spectral energy distributions (SEDs) of dust disks are widely used to
infer dust properties (compositions and sizes) and disk structures (dust
spatial distributions) which might be indicative of the presence or absence of
planets or smaller bodies like asteroids and comets in the disk. Based on
modelling of the SED of HR 4796A, a young main-sequence star with the largest
fractional infrared (IR) emission, we show that the SED alone is not a good
discriminator of dust size, spatial distribution (and composition if no
spectroscopic data are available). A combination of SED, mid-IR spectroscopy,
and coronagraphic near-IR imaging of scattered starlight and mid-IR imaging of
dust thermal emission provides a better understanding of these properties.
