HDF5 Data File Format
=====================
$Header$

This design assumes that integer min/max/size info is implicit in an
HDF5 dataset.  If not, these would need to be added as explicit attributes.

array [0:*] (timesteps) of
	array [1:N_horizons(t)] of
		# description of a single apparent horizon
		fp origin_x, origin_y, origin_z
		array [0:N_patches-1] of
			# description of a single patch
			array [min_irho:max_irho] [min_isigma:max_isigma] of h
			array [min_irho:max_irho] [min_isigma:max_isigma] of x
			array [min_irho:max_irho] [min_isigma:max_isigma] of y
			array [min_irho:max_irho] [min_isigma:max_isigma] of z
		fp centroid_x, centroid_y, centroid_z
		fp area, mass