Added comments

include/ArduinoJson/Internals/JsonVariantContent.hpp

@@ -8,18 +8,21 @@
 
 namespace ArduinoJson {
 
+// Forward declarations
 class JsonArray;
 class JsonObject;
 
 namespace Internals {
 
+// A union that defines the actual content of a JsonVariant.
+// The enum JsonVariantType determines which member is in use.
 union JsonVariantContent {
   bool asBoolean;
-  double asDouble;
-  long asLong;
-  const char* asString;
-  JsonArray* asArray;
-  JsonObject* asObject;
+  double asDouble;       // asDouble is also used for float
+  long asLong;           // asLong is also used for char, short and int
+  const char* asString;  // asString can be null
+  JsonArray* asArray;    // asArray cannot be null
+  JsonObject* asObject;  // asObject cannot be null
 };
 }
 }