function rd_band, fn, mol, iso, v_upper, v_lower

;+
; NAME:
;  rd_band
; PURPOSE: (one line)
;  Read a molecular band from a HITRAN file
; DESCRIPTION:
; CATEGORY:
;  Spectra
; CALLING SEQUENCE:
;  rd_band, fn, mol, iso, v_upper, v_lower
; INPUTS:
;  fn - the filename of a HITRAN molecular file. 
;  mol - index of molecule (or 0 for any)
;  iso - index of isotope (or 0 for any)
;  v_upper - upper vibrational quantum number, or 0 for any
;  v_lower - lower vibrational quantum number, or 0 for any
; OPTIONAL INPUT PARAMETERS:
;  none
; KEYWORD INPUT PARAMETERS:
;  none
; KEYWORD OUTPUT PARAMETERS:
;  none
; OUTPUTS:
;  Returns an array of spectral line structures
; COMMON BLOCKS:
;  None
; SIDE EFFECTS:
; RESTRICTIONS:
;  This doesn't use the main HITRAN file, but the files in the by_molec directory
; PROCEDURE:
; MODIFICATION HISTORY:
;  Written 2000 October, by Leslie Young, SwRI
;-

ln=new_specline()
openr, fp, fn, /get_lun
fs=fstat(fp)
nmax=fs.size / 102
lna=replicate(ln, nmax)

n=0L
rd_next, fp, ln, mol, iso, v_upper, v_lower, -1., -1., -1.
while ln.mol gt 0 do begin &$
  lna(n)=ln &$
  n=n+1 &$
  rd_next, fp, ln, mol, iso, v_upper, v_lower, -1., -1., -1. &$
end
close, fp

lnb = replicate(ln, n)
lnb(0:n-1) = lna(0:n-1)
return, lnb

end