!    call copen(lun,subdir,file,err)   !open "CONFIG" readonly
!    arguments are: int, char,char, logical
!    COPEN tries in 4 locations to open a "config" type file:
!    There are 4 places it looks:
!    1. Starting closest to current dir: config/file
!    1. Next closest: subdir/config/file
!    3. Then Users defined  $ACC_USERCONFIG/subdir/file 
!    4. Finally look in    $ACC_CONFIG/subdir/file 
!    4th  is  ("official"), but will not usually be current.
!    If subdir string contains no nonblanks, copen will, as
!    with "opener", Just expand file, ignore subdir and open
!    wherever the expanded filename leads.
!    If lun <= 0, then lunget will be called for it
     subroutine copen(ll,subdir,file,er)
     use cesr_utils
     implicit none
     integer ll,ierr,case,lb,le
     character*(*) file,subdir
     character*256 filex,befexp
     logical er,valid,hasconfig
     er=.false.        !assume success
     if (ll <= 0) ll = lunget()
     hasconfig=(index(file,'_CONFIG').gt.0) !try to save user that forgets and
!    includes environment variable in filename
     if((hasconfig).or.(len_trim(subdir).lt.1)) then !Oldfashioned user
      befexp=file   !save with enviroment var
      call fullfilename(file,filex,valid)
      open(unit=ll,file=trim(filex),action='read',status='old',iostat=ierr)
      if(ierr.ne.0) goto 666
     else        !there is a directory specified, so try 4 possible cases
      do case=1,4
       if(case.eq.1) filex='config/'//trim(file)
       if(case.eq.2) filex='~/config/'//trim(subdir)//'/'//trim(file)
       if(case.eq.3) filex='$ACC_USERCONFIG/'//trim(subdir)//'/'//trim(file)
       if(case.eq.4) filex='$CESR_CONFIG/'//trim(subdir)//'/'//trim(file)
       befexp=filex !file with possible enviro vars, before expand
       call fullfilename(filex,filex,valid)
       open(unit=ll,file=trim(filex),action='read',status='old',iostat=ierr)
       if((ierr.ne.0).and.(case.eq.4)) goto 666 !4 strikes!
       if(ierr.eq.0) then
        lb=len_trim(befexp) ; le=len_trim(filex)
        if((le+lb).lt.70) then
        if(copen_rpt.gt.0)  print *,'CONFIG file: '//trim(befexp)//' ie: '//trim(filex) 
        else 
         if((copen_rpt == 1))  print *,'CONFIG file: '//trim(befexp)
         if((copen_rpt == 2)) print *,'IE: '//trim(filex) 
        endif 
        return
       endif 
      enddo
     endif 
     return
666  print *,' Subroutine copen err=',ierr,'  Unit=',ll
     print *,' For file '//trim(befexp) 
     print *,' That is: '//trim(filex) 
     er=.true.
     return
     end subroutine copen