nKeyCode = lastkey()
*
do case
   case nKeyCode =  5 && UP ARROW 
      select tbl
      do while !bof() and ac_level != '4'
         skip -1
      enddo
      if bof()
         do while !eof() and ac_level != '4'
            skip 1
         enddo
      endif
   case nKeyCode =  24 && DOWN ARROW
      select tbl
      do while !eof() and ac_level != '4'
         skip 1
      enddo
      if eof()
         do while !bof() and ac_level != '4'
            skip -1
         enddo
      endif
endcase