;+
; Save the data in the PDC (!g.s[0]) to the output file.
;
; Only spectral line data can be saved to disk at this time.
;
; @examples
; <pre>
;   getnod,30
;   fileout,'mysave.fits'
;   keep
;   getnod,32
;   keep
; </pre>
;
; @version $Id: keep.pro,v 1.3 2005/05/24 21:03:48 jbraatz Exp $
;-
PRO keep
    compile_opt idl2

    if (!g.line eq 1) then begin
        ; veryify that there's something in !g.s[0]
        if (n_elements(*!g.s[0].data_ptr) gt 0) then begin
            !g.lineoutio->write_spectra,!g.s[0]
        endif else begin
            message, 'Data at location 0 is empty, nothing to keep', /info
        endelse
    endif else begin
        message, 'continuum data can not yet be kept',/info
    endelse

END