+ <news class="beta" date="2019 September 3.">
+ Applicability condition is now parametrized
+ with a generic subset of numbers.
+ </news>
+ <news class="beta" date="2019 June 2.">
+ Applicability condition parametrized
+ with an initial interval of numbers
+ allows λδ-2B to generalize both λδ-2A and λδ-1B.
+ </news>
+ <news class="beta" date="2019 April 16.">
+ Extended (λδ-2A) and restricted (λδ-1B) validity is decidable
+ (anniversary milestone).
+ </news>