WordPress at a glance
filter is not described

rss_update_period filter-hook . WP 1.0

This filter is documented in wp-includes/feed-rss2.php


add_filter( 'rss_update_period', 'filter_function_name_4394' );
function filter_function_name_4394( $string ){
	// filter...

	return $string;

Where the hook is called

In file: /wp-includes/feed-rss2-comments.php
wp-includes/feed-rss2-comments.php 56
echo apply_filters( 'rss_update_period', 'hourly' );
wp-includes/feed-rss2.php 59
echo apply_filters( 'rss_update_period', $duration );
wp-includes/feed-rdf.php 40
echo apply_filters( 'rss_update_period', 'hourly' );

Where in WP core the hook is used WordPress

Usage not found.