An application subscribing to notifications can include an XML-compliant string, not to exceed 256 characters, which will be returned in the notification payload. The string can contain user-specific information to identify a particular user. Any sensitive information should be passed with due caution and proper encryption.
See the Field Index to learn which calls use ExternalUserData.
User account activity summary alert delivery schedule. Returned if PreferenceLevel is set to UserData in GetNotificationPreferences. See "Working with Platform Notifications" for instructions on "Informational Alerts".
See the Field Index to learn which calls use SummarySchedule.