WordPress at a glance
function is not described

signup_nonce_check() WP 3.0.0

Process the signup nonce created in signup_nonce_fields().

No Hooks.

Return

Array.

Usage

signup_nonce_check( $result );
$result(array) (required)

Code of signup nonce check: wp-includes/ms-functions.php VER 5.1.1

<?php
function signup_nonce_check( $result ) {
	if ( ! strpos( $_SERVER['PHP_SELF'], 'wp-signup.php' ) ) {
		return $result;
	}

	if ( ! wp_verify_nonce( $_POST['_signup_form'], 'signup_form_' . $_POST['signup_form_id'] ) ) {
		$result['errors']->add( 'invalid_nonce', __( 'Unable to submit this form, please try again.' ) );
	}

	return $result;
}