+ /**
+ * Auth pre-register event.
+ * Runs right before a new user account is registered in the system by any authentication
+ * system as a standard app user including auto-registration systems used by LDAP,
+ * SAML, OIDC and social systems. It only includes self-registrations,
+ * not accounts created by others in the UI or via the REST API.
+ * It runs after any other normal validation steps.
+ * Any account/email confirmation occurs post-registration.
+ * The provided $userData contains the main details that would be used to create
+ * the account, and may depend on authentication method.
+ * If false is returned from the event, registration will be prevented and the user
+ * will be returned to the login page.
+ *
+ * @param string $authSystem
+ * @param array $userData
+ * @returns bool|null
+ */
+ const AUTH_PRE_REGISTER = 'auth_pre_register';
+