IBM Release 1.93 manual Grating, Hollowbox, Tiledplane

	If the two end faces are the same size and shape, all the curve
	shapes are equivalent. The end faces can be offset laterally, so that
	a fan statement can build a diagonal line.
	Parameters: matname taper taperpar xlo1 xhi1 ylo1 yhi1 zlo1 zhi1 xlo2
	xhi2 ylo2 yhi2 zlo2 zhi2
GRATING	Adds a planar grating with lines of rectangular cross-section. The
	line width and phase of the grating are arbitrary, and specified with
	user functions of the coordinate variables. Thus the grating can
	have its properties altered in a very general way during
	optimization, e.g. having its Seidel aberration coefficients controlled
	to optimize a coupling efficiency. Gratings are implemented by
	evaluating phasefunc at a grid of points in the plane, and
	constructing a phase contour map. Each grating line is generated
	by following the contours at integral multiples of 2π, and centring a
	rectangular block of total width defined by widthfunc on the contour
	line, so that the grating’s diffractive strength is also a function of
	position. Making the width too large or too small will result in the
	spaces or lines disappearing, which is one way of making a grating
	with a non-rectangular boundary. The default spacing between
	phase points is two cells, but this can cause the script to run very
	slowly, so it can be overridden with the optional parameter interval.
	The interval parameter determines the grid on which the phase and
	width functions are sampled, which influences the accuracy of the
	contour maps and hence the grating placement.
	Parameters: matname orientation xlo xhi ylo yhi zlo zhi widthfunc
	phasefunc [interval]
HOLLOWBOX	Adds a hollow box (rectangular shell) of specified outer dimensions
	and thickness. It is implemented by dividing up the rectangular
	box into 26 smaller blocks: 6 for the faces, 12 for the edges, and 8
	for the corners. This primitive is especially useful for using PMLs
	to isolate a region from its surroundings. When used with PMLs,
	the outer dimensions must be the same as those of the simulation
	domain. The PML absorption directions will be the outward
	normals for the flat faces, outward-directed face diagonals for the
	edges, and outward-directed body diagonals for the corners.
	Parameters: mattype xlo xhi ylo yhi zlo zhi thickness
TILEDPLANE	Adds a tiled plane (thick rectangular sheet) of specified outer
	dimensions. It is implemented by dividing up the rectangular sheet
	into 9 smaller blocks: 1 for the face, 4 for the edges, and 4 for the

19