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plural subdecks
(construction) The undersection of a deck (as of a bridge or a ship). examples
(journalism) A subheadline. quotations examples
If there's a strapline or subdeck, write these after the main deck and don't use the same words. A strapline goes above the main headline and a subdeck below it.
2005, Richard Keeble, Print Journalism: A Critical Introduction, page 114