Oracle documentation says Columns defined using the ROWID data type behave like other table columns: values can be updated, and so on.
Can I create a index on a column defined using ROWID data type containing rowids ?
Oracle must be right. Yes, you can.
SQL> CREATE TABLE rowid_test (c_rowid ROWID);
Table created
SQL> CREATE INDEX rowid_test_idx ON rowid_test(c_rowid);
Index created