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filter is not described

(option) filter-hook . WP 2.9.0

Filters the number of items to be displayed on each page of the list table.

The dynamic hook name, $option, refers to the per_page option depending on the type of list table in use. Possible values include: 'edit_comments_per_page', 'sites_network_per_page', 'site_themes_network_per_page', 'themes_network_per_page', 'users_network_per_page', 'edit_post_per_page', 'edit_page_per_page', 'edit_{$post_type}_per_page', etc.

Usage

add_filter( '(option)', 'filter_function_name_815' );
function filter_function_name_815( $per_page ){
	// filter...

	return $per_page;
}
$per_page(int)
Number of items to be displayed.
Default: 20

Where the hook is called

WP_List_Table::get_items_per_page()
WP_Screen::render_per_page_options()
wp-admin/includes/class-wp-list-table.php 701
return (int) apply_filters( "{$option}", $per_page );
wp-admin/includes/class-wp-screen.php 1181
$per_page = apply_filters( "{$option}", $per_page );

Where the hook is used (in WP core)

Does not used.