A class to represent a Part21 instance as defined in one Part21 file A Part21EntityInstance is defined by the following arguments: entity_name: a string entity_attributes: a list of strings to represent an attribute. For instance, the following expression: #4 = PRODUCT_DEFINITION_SHAPE('$','$',#5); will result in : entity : <class 'config_control_design.product_definition_shape'> entity_instance_attributes: ['$','$','#5']