"An implementation should support Long_Integer in addition to Integer if the target machine supports 32-bit (or longer) arithmetic. No other named integer subtypes are recommended for package Standard. Instead, appropriate named integer subtypes should be provided in the library package Interfaces (see B.2)."
Long_Integer is supported. Other standard integer types are supported so this advice is not fully followed. These types are supported for convenient interface to C, and so that all hardware types of the machine are easily available.