function get_pds_value, file, keyword
;
; Extract a value (string format) from a label
; given the keyword (string).
;
; Inputs:
;   file      - name of the PDS label file
;   keyword   - the PDS keyword
;
; Version 1.0, 18-May-2009
; T. H. Prettyman
; Planetary Science Institute

result=-1
openr, lun, file, /get_lun, error=err
if (err ne 0) then return, result

line=''
JUMP0:
readf, lun, line
test=strpos(line,keyword)
if (test ge 0) then goto, JUMP1
if (eof(lun)) then return, result
goto, JUMP0
JUMP1:

split=strtrim(strsplit(line,'=',/extract),2)
if (n_elements(split) ne 2) then return, result
result=split[1]

free_lun, lun

return, result
end