SUBROUTINE instdates(sat2lc,from,to,instdir)
c
c This subroutine finds the entire data range for the satellite with the
c two-letter designation  sat2lc .  Results are returned in  from  and
c to ,  which are character variables of length at least 7
c
c The subroutine must be able to open the file  inst.index.
c
      IMPLICIT NONE
      CHARACTER*(*) sat2lc,from,to,instdir

      CHARACTER*2 s2lcf, s2lc
      INTEGER*1   s2lci(2)
      EQUIVALENCE(s2lc,s2lci)
      CHARACTER*80 fname, lname
      CHARACTER*7  vf, vt
      INTEGER*4 lun, instdir_l, str_text_len

      from= '9999999'
      to=   '0000000'

      CALL get_lun(lun)
      
      instdir_l= str_text_len(instdir)
      lname= instdir(1:instdir_l)//'/'//'inst.index'
      OPEN(UNIT=lun,FILE=lname,
     &     FORM='formatted',STATUS='old', ERR=901)

      s2lc=sat2lc(1:2)
      IF((97.LE.s2lci(1)).AND.(s2lci(1).LE.122))s2lci(1)=s2lci(1)-32
      IF((97.LE.s2lci(2)).AND.(s2lci(2).LE.122))s2lci(2)=s2lci(2)-32


  100 READ(lun,2,END=902,ERR=903) s2lcf, vf, vt, fname
      IF(s2lc .EQ. s2lcf) THEN
        IF(vf .LT. from) from= vf
        IF(vt .GT. to)   to= vt
      END IF
      GOTO 100

  902 CONTINUE
      CLOSE(lun)
      CALL unget_lun(lun)
      RETURN

  901 CONTINUE
      WRITE(6,*)'!!! Subroutine instdates could not read index file.'
      WRITE(6,1)lname
      STOP

  903 CONTINUE
      WRITE(6,*)'Error reading the instrument data index file'
      WRITE(6,1)lname
      STOP

    1 FORMAT(A)
    2 FORMAT(A2,2X,A7,1X,A7,1X,A)

      END