[fpc-pascal]WoW

[Shifted Soul]

Lets see this code :

PROGRAM Essai;
{$MODE OBJFPC}
TYPE
 a = CLASS
     PUBLIC
      CONSTRUCTOR a1;
      x : Integer;
      DESTRUCTOR a2;
     END;
 CONSTRUCTOR a.a1;
 BEGIN
 END;

 DESTRUCTOR a.a2;
 BEGIN
 END;

VAR
 b : a;
BEGIN
 b.x := 10;
 write(b.x);
END.

As I learned in the documentation, b is a pointer that is not allocated
:
"Remember that a class is a pointer to an object, so when you declare a
variable of some class, the compiler just allocates a pointer, not the
entire object."

documentation : Reference guide : Classes
then why this code is functional ?!
This is my problem : I am using a pointer which not allocated (Am I
using a ghost memory ???!).
Please tell what's the problem (it is a bug ?).
Shifted Soul