Extensible select and enumeration types

and their elements in schema General_model_parameter_arm taking into account BASED_ON types


 assigned_name_select - EXTENSIBLE GENERIC_ENTITY SELECT
          External_class_library

 classification_item - EXTENSIBLE GENERIC_ENTITY SELECT
          Constrained_general_parameter_relationship
          General_model_parameter
          Parameter_value_representation_item

 measure_value - EXTENSIBLE SELECT
          any_number_value
          any_string_value
          length_measure
          plane_angle_measure

 parameter_value_select - EXTENSIBLE GENERIC_ENTITY SELECT
          Generic_expression
          Value_with_unit

 property_assignment_select - EXTENSIBLE SELECT

 represented_definition - EXTENSIBLE SELECT
          Assigned_property
          Independent_property