Create Reverse Key Index On Table

difference between the ways we create Reverse Key Index on the table.The two ways are as below:

1) CREATE INDEX <Index_Name> ON <Table_Name>(<Column_Name) REVERSE ;
2) CREATE INDEX <Index_Name> ON<Table_Name>(REVERSE(<Column_Name>)) ;

Which one is the appropraite one.
Are both going to act in the same way.

I created index in both ways one by one on the table.But when I fire the select statement against the same table, The explain plan doesn't show any cost and it shows the full table scan in both ways.The select statement used is as below...I want to compare the column with string RBO(i.e('RBO%') at the start.

SELECT *
FROM <Table_Name>
WHERE REVERSE (<Column_Name>) LIKE '%OBR' ;

The select statement is giving me the correct result. Only the explain plan is showing Full Table Scan.can we use this reverse with IN operator also in the same way by reversing the values.