The following complex objects can reference any of the simple objects listed in Section 3.1, Simple Objects:
Alarm
Appointment
AttachmentID
AttachmentInfo
AttachmentItemInfo
Authentication
BoxEntry
CalendarItem
CategoryRefList
ContainerItem
ContainerRef
Custom
CustomList
CustomType
Day
DayOfWeek
Distribution
DistributionType
DocumentRef
Filter
FilterDate
FilterElement
FilterEntry
FilterGroup
FilterOp
From
GMTOffset
Hour
Item
ItemClass
ItemList
ItemOptions
ItemOptionsPriority
ItemSecurity
ItemSource
ItemStatus
ItemThreading
Mail
MessageBody
MessagePart
Minute
Month
NameAndEmail
Note
OccurrenceType
PhoneFlags
PhoneMessage
Recipient
RecipientList
RecipientType
Status
Task
Timezone
TimezoneComponent
TrustedApplication
uid
UUID
WeekDay