Wrong program structure

[George <mail2george@gmx-topmail.de>]

Hi All,

GNAT is complaining about "begin" being used as identifier and a missing 
"begin" for procedure "keywords4". The progam structure is like this:

with Ada.Text_IO;
with Ada.Command_Line;
with Ada.Characters.Handling;

procedure keywords4 is

procedure Ada83 is
begin
-- some string output
end Ada83;

procedure Ada95 is
begin
-- some string output
end Ada95;

procedure Ada2005 is
begin
-- some string output
end Ada2005;

procedure Attributes is
begin
-- some string output
end Attributes;

procedure Sources is
begin
-- some string output
end Sources;

procedure Author is
begin
-- some string output
end Author;

begin
-- Ada.Command_Line.Argument_Count is "0" if
-- a) Command_Line.Argument_Count is not implemented (Compiler, OS)
-- b) no arguments given
if Ada.Command_Line.Argument_Count > 0 then
   for counter in 1..Ada.Command_Line.Argument_Count loop
      declare
      Arg : constant String := Ada.Characters.Handling.To_Upper
(Ada.Command_Line.Argument(counter));
     -- some commands
   end loop;
else -- if Argument_Count = 0 print help
   -- some commands
end if;
end keywords4;

I nested the procedures Ada83, Ada95, etc. into keywords4 because I can 
not have multiple compilation units. I tried defining a package but when 
executing the program the runtime library came back with the message that 
the code could not be executed.

Maybe I am asking simple questions. Its because I am new to Ada and try 
get used to the language.

What is the problem with the above code?

Regards

George