SAMPLE ADA PROGRAM 
 --------------------------------------------
 |  procedure Main is                       |
 |     Z  : Integer;                        |
 |   ----------------------------------|    |
 |  |  procedure Sub1 is               |    |
 |  |  begin                           |    |
 |  |     Put(Z);                      |    |
 |  |  end                             |    |
 |  |-----------------------------------    |
 |                                          |
 |   --------------------------------- |    |
 |  |  procedure Sub2 is               |    |
 |  |  Z  : Integer                    |    |
 |  |  begin                           |    |
 |  |     Z := 5;                      |    |
 |  |     Sub1;                        |    |
 |  |  end                             |    |
 |  |----------------------------------     |
 |   begin  -- of Main                      |
 |     Z := 15;                             |
 |     Sub2;                                |
 |   end;                                   |
 |------------------------------------------|

Static visibility:

In SUB1 Z=15 

Dynamic visibility:  

                    SUB1  
       SUB2 Z=5     SUB2 Z=5
MAIN   MAIN Z=15    MAIN Z=15

In SUB1 Z = 5