WordPress at a glance
filter is not described

page_css_class filter-hook . WP 2.8.0

Filters the list of CSS classes to include with each page item in the list.

Usage

add_filter( 'page_css_class', 'filter_function_name_8040', 10, 5 );
function filter_function_name_8040( $css_class, $page, $depth, $args, $current_page ){
	// filter...

	return $css_class;
}
$css_class(array)
An array of CSS classes to be applied to each list item.
$page(WP_Post)
Page data object.
$depth(int)
Depth of page, used for padding.
$args(array)
An array of arguments.
$current_page(int)
ID of the current page.

Where the hook is called

Walker_Page::start_el()
page_css_class
wp-includes/class-walker-page.php 148
$css_classes = implode( ' ', apply_filters( 'page_css_class', $css_class, $page, $depth, $args, $current_page ) );

Where the hook is used (in WP core)

Does not used.