Each table, index, and text chain has one or more Object Allocation Map (OAM) pages stored on pages allocated to the table or index. If a table has more than one OAM page, the pages are linked in a chain. OAM pages store pointers to the allocation units that contain pages for the object.
The first page in the chain stores allocation hints, indicating which OAM page in the chain has information about allocation units with free space. This provides a fast way to allocate additional space for an object and to keep the new space close to pages already used by the object.