WAL, xl_heap_insert and tuple oid mystry

Hi,
Suppose I create a table as follows:

CREATE TABLE test2 (name TEXT, age INTEGER) WITH oids;

Now, for every tuple in this table is associated with a unique oid, which I can retrieve by:

SELECT oid, name, age FROM test2;

which works great. So far so good.

Now, if look at the corresponding WAL entry for any insert into this relation, it creates the following WAL entry which I can decode.

XLogRecord ---> Followed by --> xl_heap_insert struct -->followed by --> xl_heap_header --> Followed by --> tuple data

If I use the macro  HeapTupleHeaderGetOid([xl_heap_header struct]) or equivalently if I test ([xl_heap_header struct]->t_infomask & HEAP_HASOID), it tells me that the tuple oid is not stored with this record.

Where is the OID of tuple stored in a WAL record of a tuple? If not with xl_heap_header, where is it stored? Is it stored at all?

Thanks for any responses.  
Jagan