A simple select question

I have the following three tables
Tab_W Tab_X Tab_Y Tab_Z
====== ====== ====== =============
No_W No_X No_Y No_Z
Name_W No_W No_X No_X

        Name_X Name_Y Name X

With Values

Tab_W(0001,W1)
Tab_W(0002,W2)
Tab_X(0010,0001,X1)
Tab_X(0011,0001,X2)
Tab_Y(0100,0010,Y1)
Tab_Y(0101,0010,Y2)
Tab_Y(1000,0100,Z1)
Tab_Y(1001,0100,Z2)
Tab_Y(1002,0100,Z2)

And I would like to have a listing in a hierarchical mode as follows

Level		Name1		Name2
======	=======	======
1		W1		X1
2		X1		Y1
3		Y1		Z1
3		Y1		Z2
3		Y1		Z3
1		W1		X2
2		X1		Y2		

How can I do it ?

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