Style or Format

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This, as a question, was asked of me by a fellow writer.
The Question
He wrote: “Hey…I’ve finished the second Chet Seevers (Novelette?) and have to bounce one off of you. What is the proper format for a shorter story 25k?”
“In anything longer than a really short story, I start each scene or chapter with a title ie: Foreign Object Damage or Hard Landing, etc. Which seems improper with sometimes no more than 5 or so pages between.”
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“In the original draft of this one…I have only used a centered # with spacing above and below for a scene break of sorts. Is that acceptable for a story of this length?”
“I can’t really find anything advising one way or another.”
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The Answer
The next reply from me was obvious. We’ll throw it out to the blogisphere and see what others have to say.
What is the answer for Novelette length formats? Are chapters all right? Are chapter titles all right? And regarding scene breaks, is there a rule? Or is it whatever the agent, editor, publisher dictates?
Timothy J. Desmond
Blog at: https://timdesmondblog.wordpress.com
Amazon author page at: http://www.amazon.com/-/e/B00694KQQO
Writing at: http://timothydesmond.wordpress.com
Art at: http://artbydesmond.wordpress.com