我看到这样的声明
typedef *unspecified* value_type;
typedef *unspecified* reference;
在Boost :: multi_array类的声明中.
namespace boost { template <typename ValueType,std::size_t NumDims,typename Allocator = std::allocator<ValueType> > class multi_array { public: // types: typedef ValueType element; typedef *unspecified* value_type; typedef *unspecified* reference; typedef *unspecified* const_reference; typedef *unspecified* difference_type; typedef *unspecified* iterator; typedef *unspecified* const_iterator; typedef *unspecified* reverse_iterator; typedef *unspecified* const_reverse_iterator; typedef multi_array_types::size_type size_type; typedef multi_array_types::index index; typedef multi_array_types::index_gen index_gen; typedef multi_array_types::index_range index_range; typedef multi_array_types::extent_gen extent_gen; typedef multi_array_types::extent_range extent_range; typedef *unspecified* storage_order_type;
*未指定*是什么意思?这是C11标准吗?