18 Language support library [language.support]

18.3 Implementation properties [support.limits]

18.3.2 Numeric limits [limits]

18.3.2.6 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 denormalization (variable number of exponent bits) is characterized by the values:

(1.1)
denorm_indeterminate if it cannot be determined whether or not the type allows denormalized values
(1.2)
denorm_absent if the type does not allow denormalized values
(1.3)
denorm_present if the type does allow denormalized values