WordPress at a glance
filter is not described

site_allowed_themes filter-hook . WP 4.5.0

Filters the array of themes allowed on the site.

Usage

add_filter( 'site_allowed_themes', 'filter_function_name_7558', 10, 2 );
function filter_function_name_7558( $allowed_themes, $blog_id ){
	// filter...

	return $allowed_themes;
}
$allowed_themes(array)
An array of theme stylesheet names.
$blog_id(int)
ID of the site.
Default: current site

Where the hook is called

WP_Theme::get_allowed_on_site()
wp-includes/class-wp-theme.php 1333
return (array) apply_filters( 'site_allowed_themes', $allowed_themes[ $blog_id ], $blog_id );
wp-includes/class-wp-theme.php 1383
return (array) apply_filters( 'site_allowed_themes', $allowed_themes[ $blog_id ], $blog_id );

Where the hook is used (in WP core)

Does not used.