Oracle Correlated Query Scope. Invalid Identifier Error

Consider query

[sourcecode language="sql"]
SELECT (SELECT tab.col  FROM DUAL) a
FROM (SELECT 1 col  FROM DUAL) tab;
[/sourcecode]

Output is

A
---
1

Here I am using tab table value inside subquery that is one level down and it's recognized by system.

Now, If I take it one more level down, that is, using tab value inside subquery's subquery, something like

[sourcecode language="sql"]
SELECT (SELECT * FROM (SELECT tab.col  FROM DUAL)) A
FROM (SELECT 1 col  FROM DUAL) tab
[/sourcecode]

It throws "invalid identifier TAB.COL" error

At Second level its not recognized by system.