"An implementation should support
Long_Floatin addition to
Floatif the target machine supports 11 or more digits of precision. No other named floating point subtypes are recommended for package
Standard. Instead, appropriate named floating point subtypes should be provided in the library package
Long_Long_Float are also provided. The
former provides improved compatibility with other implementations
supporting this type. The latter corresponds to the highest precision
floating-point type supported by the hardware. On most machines, this
will be the same as
Long_Float, but on some machines, it will
correspond to the IEEE extended form. The notable case is all x86
Long_Long_Float corresponds to the 80-bit
extended precision format supported in hardware on this processor.
Note that the 128-bit format on SPARC is not supported, since this
is a software rather than a hardware format.