WordPress at a glance
filter is not described

get_lastpostmodified filter-hook . WP 2.3.0

Filters the date the last post was modified.

Usage

add_filter( 'get_lastpostmodified', 'filter_function_name_3560', 10, 2 );
function filter_function_name_3560( $lastpostmodified, $timezone ){
	// filter...

	return $lastpostmodified;
}
$lastpostmodified(string)
Date the last post was modified.
$timezone(string)
Location to use for getting the post modified date. See get_lastpostdate() for accepted $timezone values.

Where the hook is called

get_lastpostmodified()
wp-includes/post.php 5930
return apply_filters( 'get_lastpostmodified', $lastpostmodified, $timezone );

Where the hook is used (in WP core)

Does not used.