What is the meaning of "select * from relational(owner.table)"? We recently got some errors in our alert log of the form

301598: Tue Jul 16 03:58:29 2013
301599: ORA-01555 caused by SQL statement below 
301600: SELECT * FROM RELATIONAL(&lt;owner&gt;.&lt;table&gt;)


I know how to handle ORA-01555 errors, but I never encountered something like SELECT * FROM RELATIONAL. I looked in DBA_OBJECTS, but there is no such function/operator/whatever.

Googling for 'SELECT * FROM RELATIONAL' only returned questions related to ORA-01555.

So, my question is: What is the meaning of the RELATIONAL keyword here?
It appears to be inert. I tested this on XE 11 and found that it does nothing.

CREATE TABLE dbausers AS SELECT * FROM dba_users;

-- Function doesn't affect result set.
SELECT * FROM dbausers
MINUS
SELECT * FROM RELATIONAL(dbausers);

SELECT * FROM RELATIONAL(dbausers)
MINUS
SELECT * FROM dbausers;