; SOP : Slant Offset Polynomials (for a given nso at a given column). */
; forward is: (pixel slant offset) = func(rowoff) .. */

function nsxng_SOPtype
;  common nsx
  c = nsxng_constants()
  MAXSP = c.MAXSP
  
; NIRES Calibration Parameter for each echelle order.
  SOPstructure = { $
                 xoff: dblarr(MAXSP),$   ;        /* xoff value for each column of SOP[nso] */
                 coef: dblarr(MAXSP,3) $ ;     /* coeffecients (order=2) for each column of SOP[nso] */
                 }

  return, create_struct(name="SOP",SOPstructure) 

end