COMMON hess_design,	hs_X	,$ ; Rowland Diameter
;
; INPUT parameters
			hs_Xoff	,$ ; On-axis vertex location at Xg = Xoff
				   ; --------------------------
				   ;   HYPERBOLA specification (each shell)
			hs_HAf	,$ ; Hyperbola Axial distance to focus, front
			hs_HAb	,$ ; Hyperbola Axial distance to focus, back
			hs_HRf	,$ ; Hyperbola Radius, front
			hs_HRb	,$ ; Hyperbola Radius, back
				   ; --------------------------
				   ;   GRATING FRAME parameters (each shell)
			hs_Doff	,$ ; Distance from grating center to hole cntr
			hs_Dthk	,$ ; Distance from grating membrane to mounting
				   ;	surface
			hs_Dspc	,$ ; Spacing between grating mounting holes
			hs_Disp	,$ ; Dispersion angle offset from Y axis
				   ; --------------------------
				   ;   SEGMENT parameters
			hs_Segs ,$ ; Names of all the segments
			hs_GpS	,$ ; Gratings per segment
			hs_Tglu	,$ ; Glue angles (nominal, each segment)
				   ; The real grating glue angle is this
				   ; value plus hs_Disp.
				   ; --------------------------
;   OUTPUT values
;
; Center of grating location
			hs_XC	,$ ; X location of grating center
			hs_YC	,$ ; Y location of grating center
			hs_ZC	,$ ; Z location of grating center
; Unit vector perp to grating membrane towards HRMA
			hs_XU	,$ ; X
			hs_YU	,$ ; Y
			hs_ZU	,$ ; Z
; Unit vector parallel to grating lines
			hs_XUL	,$ ; X
			hs_YUL	,$ ; Y
			hs_ZUL	,$ ; Z
; Unit vector perp to grating lines
			hs_XUD	,$ ; X
			hs_YUD	,$ ; Y
			hs_ZUD	,$ ; Z
; Unit vector in mounting hole direction (in plane)
			hs_XUMH	,$ ; X
			hs_YUMH	,$ ; Y
			hs_ZUMH	,$ ; Z
; Angular error due to mounting hole unit vector:
			hs_Terror, $ ; Theta error
; Mounting hole coordinates
			hs_XMH	,$ ; X location of hole axis-surface intersec.
			hs_YMH	,$ ; Y
			hs_ZMH	,$ ; Z
;
;
;	NOTE:  variables in common obey:
;
;		ALL lengths in mm
;		ALL angles in radians
;
;
;  CUSTOMIZATION parameters
;
;  For output (hess_plot and hess_out) inches is available:
			hs_use_inches	; if non zero inches are used
					;  for the output programs