Merge pull request MicrosoftDocs#116 from MicrosoftDocs/corob-msft-patch-6

Update std-specify-language-standard-version.md

Author: mikeblome

docs/build/reference/std-specify-language-standard-version.md

@@ -50,10 +50,12 @@ The **/std:c++17** option enables the full set of C++17 features implemented by
 
 The **/std:c++latest** option enables the set of C++ language and library features implemented by Visual C++ to track the most recent Working Draft and defect updates of the C++ Standard. Use this switch to get the latest language features supported by the compiler. For a list of supported language and library features, see [What's New for Visual C++](../../what-s-new-for-visual-cpp-in-visual-studio.md). The **/std:c++latest** option does not enable features guarded by the **/experimental** switch.  
 
+The **/std** option in effect during a C++ compilation can be detected by use of the [\_MSVC\_LANG](../preprocessor/predefined-macros.md) preprocessor macro. For more information, see [Preprocessor Macros](../preprocessor/predefined-macros.md).
+
 The **/std:c++14** and **/std:c++latest** options are available beginning in Visual C++ 2015 Update 3. The **/std:c++17** option is available beginning in Visual C++ 2017 Update Version 15.3.  
 
-> [!NOTE]
->  Depending on the Visual C++ compiler version or update level, certain C++14 features may not be fully implemented or fully conformant when you specify the **/std:c++14** option. For example, the Visual C++ 2017 RTM compiler does not fully support C++14-conformant `constexpr`, expression SFINAE, or 2-phase name lookup. For an overview of C++ language conformance in Visual C++, see [Visual C++ Language Conformance](../../visual-cpp-language-conformance.md). 
+ [!NOTE]
+> Depending on the Visual C++ compiler version or update level, certain C++14 features may not be fully implemented or fully conformant when you specify the **/std:c++14** option. For example, the Visual C++ 2017 RTM compiler does not fully support C++14-conformant `constexpr`, expression SFINAE, or 2-phase name lookup. For an overview of C++ language conformance in Visual C++, see [Visual C++ Language Conformance](../../visual-cpp-language-conformance.md). 
   
 ### To set this compiler option in the Visual Studio development environment