Here are the data structures with brief descriptions:

CFILETIME
Cpst_binary	Simple wrapper for binary blobs
Cpst_block_recorder	This is only used for internal debugging
Cpst_desc_tree
Cpst_entryid
Cpst_file
Cpst_id2_tree
Cpst_index_ll
Cpst_item	This contains the common mapi elements, and pointers to structures for each major mapi item type
Cpst_item_appointment	This contains the appointment related mapi elements
Cpst_item_attach	This contains the attachment related mapi elements
Cpst_item_contact	This contains the contact related mapi elements
Cpst_item_email	This contains the email related mapi elements
Cpst_item_extra_field	Linked list of extra header fields
Cpst_item_folder	This contains the folder related mapi elements
Cpst_item_journal	This contains the journal related mapi elements
Cpst_item_message_store	This contains the message store related mapi elements
Cpst_recurrence	This contains the recurrence data separated into fields
Cpst_string	The string is either utf8 encoded, or it is in the code page specified by the containing mapi object
Cpst_varbuf
Cpst_x_attrib_ll	Linked list of extended attributes