Integer; procedure bigsub is procedure a(flag : boolean) is

Procedure Bigsub is
       procedure A (Flag: Boolean ) is
         v,w : Integer
       procedure B is
         u,y : Integer
            A(false);
          end; -- of B
if flag
then B;
else C;
    ...
end; -- of A
procedureC is
u,w,y : Integer;

procedure D is
t,z : Integer
   ...
z = t*u + y-w;
   ...
end; -- of D
        ...
D;
end; -- of C
begin
       t,u,v : Integer
              ...
             A(true);
              ...
            end; -- of BigSub

Where is the picture at