17 Language support library [language.support]

17.3 Implementation properties [support.limits]

17.3.3 Floating-point type properties [fp.style]

17.3.3.2 Type float_­denorm_­style [denorm.style]

namespace std {
  enum float_denorm_style {
    denorm_indeterminate = -1,
    denorm_absent = 0,
    denorm_present = 1
  };
}
The presence or absence of subnormal numbers (variable number of exponent bits) is characterized by the values: