Extensible select and enumeration types

and their elements in schema Single_part_representation_arm taking into account BASED_ON types


 documented_element_select - EXTENSIBLE SELECT
          Part
          Part_version
          Part_view_definition

 external_identification_item - EXTENSIBLE GENERIC_ENTITY SELECT
          Document_definition
          File

 identification_item - EXTENSIBLE SELECT

 measure_value - EXTENSIBLE SELECT
          any_number_value
          any_string_value
          length_measure
          plane_angle_measure

 organization_or_person_in_organization_item - EXTENSIBLE SELECT
          Document
          Document_definition
          Document_version
          Part
          Part_version
          Part_view_definition

 property_assignment_select - EXTENSIBLE SELECT
          Part_view_definition

 represented_definition - EXTENSIBLE SELECT
          Assigned_property
          Independent_property