WordPress at a glance
filter is not described

wp_revisions_to_keep filter-hook . WP 3.6.0

Filters the number of revisions to save for the given post.

Overrides the value of WP_POST_REVISIONS.

Usage

add_filter( 'wp_revisions_to_keep', 'filter_function_name_8578', 10, 2 );
function filter_function_name_8578( $num, $post ){
	// filter...

	return $num;
}
$num(int)
Number of revisions to store.
$post(WP_Post)
Post object.

Where the hook is called

wp_revisions_to_keep()
wp-includes/revision.php 505
return (int) apply_filters( 'wp_revisions_to_keep', $num, $post );

Where the hook is used (in WP core)

Does not used.