The safe range might include other values as well. Otherwise, the subtype is unconstrained. There is a predefined, unconstrained, floating point subtype named Float, declared in the visible part of package Standard. In an implementation that supports floating point types with 6 or more digits of precision, the requested decimal precision for Float shall be at least 6. Different predefined floating point types are allowed to have the same base decimal precision.
Corresponding recommendations apply to any other predefined floating point types.
There need not be a named floating point type corresponding to each distinct base decimal precision supported by an implementation. No other named floating point subtypes are recommended for package Standard. Email comments, additions, corrections, gripes, kudos, etc.