WordPress at a glance
filter is not described

wpmu_active_signup filter-hook . WP 3.0.0

Filters the type of site sign-up.

Usage

add_filter( 'wpmu_active_signup', 'filter_function_name_4208' );
function filter_function_name_4208( $active_signup ){
	// filter...

	return $active_signup;
}
$active_signup(string)
String that returns registration type. The value can be 'all', 'none', 'blog', or 'user'.

Where the hook is called

In file: /wp-signup.php
wpmu_active_signup
wp-signup.php 822
$active_signup = apply_filters( 'wpmu_active_signup', $active_signup );

Where the hook is used (in WP core)

Does not used.