c++ - "reserved for the implementation"的含义

Question

正在阅读来自 What are the rules about using an underscore in a c identifier 的答案我偶然发现了以下引文:

From the 2003 C++ Standard:

17.4.3.2.1 Global names [lib.global.names]

Certain sets of names and function signatures are always reserved to the implementation:

• Each name that contains a double underscore (_ _) or begins with an underscore followed by an uppercase letter (2.11) is reserved to the implementation for any use.
• Each name that begins with an underscore is reserved to the implementation for use as a name in the global namespace.¹⁶⁵

¹⁶⁵⁾ Such names are also reserved in namespace ::std (17.4.3.1).

reserved for the implementation 到底是什么意思？

Answer 1

就是这个意思。这意味着，只有在提供编译器或标准库实现时才允许创建此类名称。