Extensible select and enumeration types

and their elements in schema Qualifications_arm taking into account BASED_ON types


 certification_item - EXTENSIBLE GENERIC_ENTITY SELECT
          Qualification_assignment

 classification_item - EXTENSIBLE GENERIC_ENTITY SELECT
          Qualification_type

 date_or_date_time_item - EXTENSIBLE SELECT
          Qualification_assignment

 organization_or_person_in_organization_item - EXTENSIBLE SELECT
          Qualification_assignment
          Qualification_type

 qualifications_select - EXTENSIBLE GENERIC_ENTITY SELECT
          Organization
          Person
          Person_in_organization