Extensible select and enumeration types

and their elements in schema Physical_breakdown_arm taking into account BASED_ON types


 breakdown_item - EXTENSIBLE SELECT
          Breakdown_element_definition
          Breakdown_element_usage

 measure_value - EXTENSIBLE SELECT
          any_number_value
          any_string_value
          length_measure
          plane_angle_measure

 product_item - EXTENSIBLE SELECT
          Product_view_definition
          View_definition_usage

 property_assignment_select - EXTENSIBLE SELECT
          Breakdown_element_realization
          Breakdown_element_usage

 represented_definition - EXTENSIBLE SELECT
          Assigned_property
          Independent_property