add const sv Pseudo_Header_Forwarded = ":pEp:MIME:attachment1:forwarded";

src/pEpMIME_internal.cc

@@ -68,6 +68,8 @@ namespace pEpMIME
 
     const sv Pseudo_Header_Format = ":pEp:MIME:longmsg:format";
     const sv Pseudo_Header_Delsp  = ":pEp:MIME:longmsg:delsp";
+    
+    const sv Pseudo_Header_Forwarded = ":pEp:MIME:attachment1:forwarded";
 
 } // end of namespace pEpMIME
 

src/pEpMIME_internal.hh

@@ -15,7 +15,7 @@
 #   include <string_view>
     typedef std::string_view sv;
 
-#else
+#else // in C++11 / C++14 use boost::string_view instead.
 #   include <boost/utility/string_view.hpp>
     typedef boost::string_view sv;
 
@@ -35,7 +35,7 @@
     
     namespace pEpMIME { using ::operator+=; }
     
-#endif
+#endif // C++17 switch
 
 
 #ifdef LOG_TO_STDERR
@@ -97,8 +97,12 @@ namespace pEpMIME
         return (str!=nullptr) && (str[0] != '\0');
     }
 
+    // extracted from Content-Type of 1st "text/plain" MIME leaf:
     extern const sv Pseudo_Header_Format;
     extern const sv Pseudo_Header_Delsp;
+    
+    // extracted from Content-Type of 1st "message/rfc822" leaf:
+    extern const sv Pseudo_Header_Forwared;
 
 } // end of namespace pEpMIME