Description
bool 
ibase_rollback_ret ( [resource link_or_trans_identifier] )
     If called without an argument, this function rolls back the default transaction 
     of the default link. If the argument is a connection identifier, the default 
     transaction of the corresponding connection will be rolled back. If the argument
     is a transaction identifier, the corresponding transaction will be rolled back.
     The transaction context will be retained, so statements executed from within
     this transaction will not be invalidated.
     Returns TRUE on success or FALSE on failure.