program Procedure_Calling_A_Procedure;

procedure One;

begin

   Writeln('This is procedure one');

end;
procedure Two;

begin

   One;

   Writeln('This is procedure two');

end;
procedure Three;

begin

   Two;

   Writeln('This is procedure three');

end;
begin  (* main program *)

   One;

   Writeln;

   Two;

   Writeln;

   Three;

end. (* of main program *)


Result of execution

This is procedure one
This is procedure one

This is procedure two
This is procedure one

This is procedure two

This is procedure three