type = struct PageHeaderData { 0 | 8 */ PageXLogRecPtr pd_lsn; 8 | 2 */ uint16 pd_checksum; 10 | 2 */ uint16 pd_flags; 12 | 2 */ LocationIndex pd_lower; 14 | 2 */ LocationIndex pd_upper; 16 | 2 */ LocationIndex pd_special; 18 | 2 */ uint16 pd_pagesize_version; 20 | 0 */ ItemIdData pd_linp[];.

type = struct HeapPageSpecialData { 0 | 8 */ TransactionId pd_xid_base; 8 | 8 */ TransactionId pd_multi_base; 16 | 4 */ ShortTransactionId pd_prune_xid; 20 | 4 */ uint32 pd_magic; total size (bytes): 24 */.