The BOOKMARK data type is an unsigned long integer that marks the position of data in a table.
MAPI defines three bookmarks, listed as follows:
Marks the beginning position of the table.
Marks the current position in the table.
Marks the ending position of the table.
Bookmarks are valid only while the table is open.
You can create custom bookmarks to suit the needs of your messaging client.
Before closing the associated table, clients must free any bookmarks that they have created.