WordPress at a glance
filter is not described

root_rewrite_rules filter-hook . WP 1.5.0

Filters rewrite rules used for root-level archives.

Likely root-level archives would include pagination rules for the homepage as well as site-wide post feeds (e.g. /feed/, and /feed/atom/).

Usage

add_filter( 'root_rewrite_rules', 'filter_function_name_789' );
function filter_function_name_789( $root_rewrite ){
	// filter...

	return $root_rewrite;
}
$root_rewrite(array)
The root-level rewrite rules.

Where the hook is called

WP_Rewrite::rewrite_rules()
wp-includes/class-wp-rewrite.php 1286
$root_rewrite = apply_filters( 'root_rewrite_rules', $root_rewrite );

Where the hook is used (in WP core)

Does not used.