ROWID ? or other internal ID - Mailing list pgsql-odbc

I'm beginner with postgresql.
In other database like ORACLE or PROGRESS you've got an internal identifier
ROWID or RECID
(bookmark with access) which allow you to select a row very quickly or to go
back to a specific row very quickly.
these functions uses an internal ID.

Does something approaching that exist under postgresql ?
I've search and found nothing except "SERIAL" but that's not an internal ID.

thanks,

Stéphane Valcauda