Extensible select and enumeration types

and their elements in schema Planned_characteristic_arm taking into account BASED_ON types


 activity_item - EXTENSIBLE GENERIC_ENTITY SELECT

 assigned_name_select - EXTENSIBLE GENERIC_ENTITY SELECT
          External_class_library

 built_in_functions - EXTENSIBLE ENUMERATION
          attr_val

 constants - EXTENSIBLE SELECT
          any_number_value
          any_string_value
          Logical_representation_item

 date_or_date_time_item - EXTENSIBLE SELECT

 documented_element_select - EXTENSIBLE SELECT
          Product
          Product_configuration
          Product_version
          Product_view_definition
          Property_value_representation
          Rule_set

 expression_syntax - EXTENSIBLE ENUMERATION
          express

 external_identification_item - EXTENSIBLE GENERIC_ENTITY SELECT
          Document_definition
          File
          User_defined_library_or_dictionary

 identification_item - EXTENSIBLE SELECT
          Requirement
          Requirement_version
          Requirement_view_definition
          Rule_set

 measure_value - EXTENSIBLE SELECT
          any_number_value
          any_string_value
          length_measure
          plane_angle_measure

 organization_or_person_in_organization_item - EXTENSIBLE SELECT
          Rule_action

 requirement_assignment_item - EXTENSIBLE SELECT

 requirement_source_item - EXTENSIBLE SELECT