WordPress at a glance
filter is not described

signup_user_meta filter-hook . WP 4.8.0

Filters the metadata for a user signup.

The metadata will be serialized prior to storing it in the database.

Usage

add_filter( 'signup_user_meta', 'filter_function_name_3911', 10, 4 );
function filter_function_name_3911( $meta, $user, $user_email, $key ){
	// filter...

	return $meta;
}
$meta(array)
Signup meta data.
Default: empty array
$user(string)
The user's requested login name.
$user_email(string)
The user's email address.
$key(string)
The user's activation key.

Where the hook is called

wpmu_signup_user()
wp-includes/ms-functions.php 789
$meta = apply_filters( 'signup_user_meta', $meta, $user, $user_email, $key );

Where the hook is used (in WP core)

Does not used.