ingres_autocommit() is called before opening a transaction (before the first call to ingres_query() or just after a call to ingres_rollback() or ingres_autocommit()) to switch the "autocommit" mode of the server on or off (when the script begins the autocommit mode is off).
When the autocommit mode is on, every query is automaticaly commited by the server, as if ingres_commit() was called after every call to ingres_query().
See also ingres_query(), ingres_rollback() and ingres_commit().