; from nsx.c
; Return an empty SPX structure

function nsxng_SPXtype

  c = nsxng_constants()
  MAXasp = c.MAXasp
  MAXabk = c.MAXabk
  MAXSP = c.MAXSP
  MAXPRO = c.MAXPRO
  
; NIRES Calibration Parameter for each echelle order.
  SPXstructure = { $
                 nsp : 0, $                                    ;                           /* SPX[0]: number of background regions. */
                 asp1 : dblarr(MAXasp), asp2:dblarr(MAXasp), $ ;  /* SPX[0]: Object window boundaries (as pixels for each order). */
                 nbk : 0,$                                     ;                           /* SPX[0]: number of background regions. */
                 abk1:dblarr(MAXabk),abk2:dblarr(MAXabk),$       ;  /* SPX[0]: Background window(s) boundaries (as arcseconds). */
                 pflx:dblarr(MAXasp),$                           ;       /* SPX[0]: Profile object flux. */
                 sigs:dblarr(MAXasp),$                           ;       /* SPX[0]: Profile object sigmas. */
                 peak:dblarr(MAXasp),$                           ;       /* SPX[0]: Profile object peak. */
                 pro_cen:0.,$                                    ;            /* Centroid of main object in arcseconds in each order. */
                 numpro:0,$                                      ;             /* Number of points in profile, i.e. nsxng_minwith(). */
                 pro_apn:0,$                                     ;            /* Number of elements in pro_apx[] and pro_apymed[] and pro_apyave[] . */
                 pro_apx:dblarr(MAXPRO),$                        ;    /* Arcsecond profile (arcseconds) (SPX[0] is average). */
                 pro_apymed:dblarr(MAXPRO),$                     ; /* Arcsecond profile (median)  (SPX[0] is sum). */
                 pro_apyave:dblarr(MAXPRO),$                     ; /* Arcsecond profile (average)  (SPX[0] is sum). */
                 numsp:0,$                                       ;              /* Number of points in spectrum. */
                 spobj:dblarr(MAXSP),$                           ;       /* object spectrum sum of counts per second in object window (per column). */
                 sperr:dblarr(MAXSP),$                           ;       /* object spectrum error. */
                 spbck:dblarr(MAXSP),$                           ;       /* background spectrum per second (average over pixels in background window(s)). */
                 spsky:dblarr(MAXSP),$                           ;       /* sky spectrum per second (average over pixels in object window). */
                 spwav:dblarr(MAXSP),$                           ;       /* wavelength in Angstroms. */
                 spdsp:dblarr(MAXSP),$                           ;       /* dispersion: angstroms/pixel. */
                 sprow:dblarr(MAXSP),$                           ;       /* image row value of object spectrum. */
                 spatm:dblarr(MAXSP),$                           ;       /* atmospheric transmission. */
                 spoac:dblarr(MAXSP),$                           ;       /* object with atmospheric correction (spectrum divided by atmospheric transmission). */
                 speac:dblarr(MAXSP)$                            ;       /* error with atmospheric correction (error divided by atmospheric transmission). */
                 }
  return, create_struct(name="SPX", SPXstructure)

end