This manual contains useful information in writing programs using the GNAT compiler. It includes information on implementation dependent characteristics of GNAT, including all the information required by Annex M of the standard.
Ada 95 is designed to be highly portable,and guarantees that, for most programs, Ada 95 compilers behave in exactly the same manner on different machines. However, since Ada 95 is designed to be used in a wide variety of applications, it also contains a number of system dependent features to Functbe used in interfacing to the external world.
Note: Any program that makes use of implementation-dependent features may be non-portable. You should follow good programming practice and isolate and clearly document any sections of your program that make use of these features in a non-portable manner.