WordPress at a glance
filter is not described

get_post_modified_time filter-hook . WP 2.8.0

Filters the localized time a post was last modified.

Usage

add_filter( 'get_post_modified_time', 'filter_function_name_9919', 10, 3 );
function filter_function_name_9919( $time, $d, $gmt ){
	// filter...

	return $time;
}
$time(string)
The formatted time.
$d(string)
The date format. Accepts 'G', 'U', or php date format.
Default: 'U'
$gmt(true/false)
Whether to return the GMT time.
Default: false

Where the hook is called

get_post_modified_time()
wp-includes/general-template.php 2539
return apply_filters( 'get_post_modified_time', $time, $d, $gmt );

Where the hook is used (in WP core)

Does not used.