Punctuation:  Use the period, space punctuation to separate the serial title from the numeric designation.  Use the comma, space punctuation to separate the numeric designation from the part title.

Theatrical serials are always intended to be viewed in a specified order.  Therefore numeric designation and part titles are usually available on the preferred source or in other sources.

245 00 $a Perils of Nyoka. $n Chapter 9, $p Burned alive.

245 00 $a Captain Midnight. $n Chapter 14, $p Scourge of revenge.

245 04 $a The trail of the octopus. $n Episode 2, $p The purple dagger.

245 04 $a The adventures of Rex and Rinty. $n Ch. 1.

If the preferred source and/or other sources use the terms such as "Chapter," "Episode," and/or "Number" interchangeably, choose the one that predominates.  If a term is supplied, enclose it in brackets.

245 04 $a The trail of the octopus. $n Episode 5, $p The eye of Satan.
(The word "episode" appears on the work.)

245 04 $a The trail of the octopus. $n Episode 7, $p The dance of death.
(The word "episode" appears in secondary source.)

245 04 $a The trail of the octopus. $n [Episode] 9, $p The chained soul.
(The word "chapter" appears on the work.)

If the work and/or secondary sources show no predominant usage, or if no term is found, supply the term "No." enclosed in brackets.

245 04 $a The purple mask. $n [No.] 12, $p Vault of mystery.

When a serial contains more than one unit per episode and the designations "Part 1" and "Part 2," etc. appear on the works or in secondary sources, do not include this designation as part of the title.  In this case, "Part 1" and "Part 2" represent unit numbers not episode numbers and should be placed in the line of physical description.

245 00 $a Perils of Nyoka. $n Chapter 9, $p Burned alive.

300 ## $a 2 film reels of 2 (20 min., 1,800 ft.) : $b sd., b&w ; $c 35 mm. $3 viewing copy.

(Film is 2 reels in length; Part 1 and Part 2 appear on reels.)

--not--

245 00 $a Perils of Nyoka. $n Chapter 9, $p Burned alive. $n Part 1.

245 00 $a Perils of Nyoka. $n Chapter 9, $p Burned alive. $n Part 2.

For theatrical serials that do not have part titles, but have only numeric designations, use them as part of the title proper, using the appropriate term as described above.

245 04 $a The adventures of Rex and Rinty. $n Ch. 1.

See also:

1B1.  Title proper of television series, theatrical serials, newsreels, and non-television educational and technical series intended to be viewed consecutively

1B.  Title proper

1.  Title and Statement of Responsibility Area