Mariner Books, a division of Houghton Mifflin Harcourt, was established in 1997 as a publisher of fiction, non-fiction, and poetry in paperback. Mariner is also the publisher of the Harvest imprint backlist, formerly published by Harcourt Brace/Harcourt Brace Jovanovich.
Mariner Books has a separate department for fiction, non-fiction, and poetry books.
The context makes no specific claim as to how Mariner Books is organized. It is within the scope of the given task that they may have separate departments for each type of literature.