Learning Ada-What does this mean.

[vashwath@rediffmail.com (prashna)]

Hi all,
1)Have a look at following piece of code and pls let me what does it
mean?
   type T_MEM_IO is
      record
         INT_1    : T_INTEGER;
         INT_2    : T_INTEGER;
      end record;
   for T_MEM_IO use
      record
         INT_1 at 0 range 0..31;
         INT_2 at 1 range 0..31;
      end record;

2)The code shown above is compiling perfectly when compiled using
tartan compiler(on AIX), but giving error when compiled using gnat(on
windows 2000).Why is it so?

Any help will be appriciated.