Section 8-410. Absentee voting; method of

The absentee voter shall mark an
  absentee ballot as provided for paper ballots or  ballots  prepared  for
  counting  by  ballot counting machines. He shall make no mark or writing
  whatsoever upon the ballot, except as above prescribed,  and  shall  see
  that  it bears no such mark or writing. He shall make no mark or writing
  whatsoever on the outside of the ballot. After  marking  the  ballot  or
  ballots  he shall fold each such ballot and enclose them in the envelope
  and seal the envelope.  He shall then take and subscribe the oath on the
  envelope, with blanks properly filled in. The envelope,  containing  the
  ballot  or  ballots,  shall  then be mailed or delivered to the board of
  elections of the county or city of his residence.