WordPress at a glance
filter is not described

(type)_template_hierarchy filter-hook . WP 4.7.0

Filters the list of template filenames that are searched for when retrieving a template to use.

The last element in the array should always be the fallback template for this query type.

Possible values for $type include: 'index', '404', 'archive', 'author', 'category', 'tag', 'taxonomy', 'date', 'embed', 'home', 'frontpage', 'page', 'paged', 'search', 'single', 'singular', and 'attachment'.

Usage

add_filter( '(type)_template_hierarchy', 'filter_function_name_5619' );
function filter_function_name_5619( $templates ){
	// filter...

	return $templates;
}
$templates(array)
A list of template candidates, in descending order of priority.

Where the hook is called

get_query_template()
wp-includes/template.php 41
$templates = apply_filters( "{$type}_template_hierarchy", $templates );

Where the hook is used (in WP core)

Does not used.