anchor.diff:    ;
   
   udp_instantiation
  -  : udp_identifier drive_strength? delay2? udp_instance (COMMA udp_instance)* SEMI
  +  : udp_identifier drive_strength delay2? udp_instance (COMMA udp_instance)* SEMI
  +  | udp_identifier delay2 udp_instance (COMMA udp_instance)* SEMI
     ;
   
   udp_instance
  
positive.code: 
  module_common_item
    : module_or_generate_item_declaration
    | interface_instantiation
    | program_instantiation
    | assertion_item
    | bind_directive
    | continuous_assign
  
negative.code:   : attribute_instances parameter_override
    | attribute_instances gate_instantiation
    | attribute_instances udp_instantiation
    | attribute_instances module_common_item
    ;
  
  